5E Alternate Casting System
The traditional D&D system for magic is terrific and, excluding some minor tweaks, has remained relatively intact since the days of AD&D. When 5E came out, I was pleased with all the changes made streamlining and improving traditional concepts, except for the lack of magic changes. Concentration is a good idea, but I wanted something that was a bit more free form. As the popularity of 5E grew, I have seen a few homebrews that got me thinking and lead to what you are reading now. Nothing against Vancian magic, but I like my magic little more free form, and while this is not as free form as I'd like it to be, the system that you'll read is one I feel is a good compromise.
At first glance, the Alternate Casting System might seem a bit constrictive or too retaliatory for rolling a fumble, but keep in mind that in a system that doesn't restrict the amount of magic cast, a balance has to be worked in some kind of way.
Lastly, I'd like to remind everyone that this is meant for you to toy with. If you come up with a better idea, then add it and repost it. This is for everyone to have fun with and not to be the end design for how casting should be handled.
Casting a Spell
In the Alternate Casting System, the only prerequisite to casting a spell is having access to the spell's level, and access to the spell itself through a spellbook and granted to you from a more powerful being, like a god or patron. Characters can attempt to cast a spell as often as they wish, but doing so, will require a spell-casting check (By rolling 1d20 and adding your spell-casting ability modifier + your proficiency bonus to your roll to beat the DC of the spells level). If the character is successful, then the spell is cast as usual. If the spell casting check fails, all it means is that the caster has some trouble corralling the energy to cast the spell, and it is not cast that round. The caster then makes another roll the next round to cast the spell. This will repeat until a successful casting roll is made or a fumble is rolled by rolling a natural 1 on a d20, or the cast stops casting.
Like in standard 5E, a caster can still cast a cantrip, and a reaction spell in the same round. If the reaction spell is not a cantrip, they will need to still roll a spell-casting check at the reaction spells level. Spells designated as a cantrip do not require a DC roll to see if they are successfully cast and are cast normally.
Each time that a caster attempts to cast a spell that is not a cantrip, that player must roll a spell-casting checkand either meet or beat the DC for the level of the spell attempted.
No Auto Success Casting
As a character increases in levels and becomes more powerful, there will come a time that their proficiency bonus and spell casting stat modifier combined is higher than the DC for casting a spell of that level. When this occurs, the character still needs to roll a 1d20 to make sure that they do not roll a fumble.
In a system where a caster has no limit to the number of spells that they can cast, implementing drawbacks is essential to maintaining game balance. Spells will take longer to cast in some occasions and even backfire with deadly results.
Some spells require the caster to make an attack roll to determine whether the spell effect hits the intended target. Your attack bonus with a spell attack equals your spell-casting ability modifier + your proficiency bonus. These are the same modifiers used when you roll a spell-casting check to determine if the spell is successfully cast. We suggest that you roll once to determine if their spell-casting check was successful and then use the same number to see if you successfully hit the targets AC.
Cantrips that require a successful to-hit roll, of course, are unaffected as cantrips, along with ritual spells, do not require a spell-casting check.
Spell Level and Casting at Higher Levels
In standard 5E spell-casting, some spells allow you to cast the spell with a higher spell slot for a higher intensity result. With Alternate Casting, you can cast any spell at your current level, spells at a higher level only unlock as your character increases in levels. Keep in mind that with the Alternate Casting rules, characters will unlock the ability to cast higher level spells much faster than you do in a traditional Vancian system. At character level 9, a wizard has unlocked the ability to cast 9th level spells. Keep in mind, though, that the higher a spells level, the greater the backlash of a fumbled spell casting roll becomes.
Most spells require a single action to cast, but some spells require a bonus action, a reaction, or more time to cast. This remains in effect for the Alternate Casting system and only changes when a caster fails a spell-casting DC check. The spell-casting DC check occurs at the end of the duration required to cast the spell, so for spells that take multiple actions or a certain amount of time, like in the case of ritual spells, the time must still elapse.
When a spell-casting DC roll fails and is not a fumble, the caster is still casting the spell, and it will carry over into the next round of combat or action. The full duration of longer spells is not required to be retaken in full, but simply another roll is made.
If a fumble is rolled, the intended spell does not occur, but the result of the fumble chart will take its place instead.
If a caster fails their spell-casting check, but the result is not a fumble, the caster can stop the spell altogether and cast another spell if applicable, as in the case of casting a cantrip or reaction spell. If the caster chooses to continue casting the same spell, they cannot cast a cantrip or a reaction spell as they are still in the act of casting the original spell until it goes off.
Bonus Action and Reaction Spells
The casting times of these spells are unchanged from the standard 5E rules.
Longer Casting Times
Certain spells (including spells cast as rituals) require more time to cast: minutes or even hours. When you cast a spell with a casting time longer than a single action or reaction, you must spend your action each turn casting the spell until the spell takes effect, and you must maintain your concentration. At the same time, if your concentration is broken, the spell fails, but you don't expend a spell slot. If you want to try casting the spell again, you must start over.
Certain spells allow for the caster to take their time to cast them, and in the standard 5E rules, one of the benefits of this is so that a spell slot is not consumed. Because there are no spell slots in the Alternate Casting System, this benefit is lost, but ritual spells because of their extra attention to detail do not require that the caster roll a spell-casting check.
Known and Prepared Spells
In the standard rules, casters must prepare what spells that they are memorizing or readying for that day. In the Alternate Casting System, this is not the case. Casters have access to all of their spells at all times. Once learned, or granted by a patron or deity, the caster will always have access. However, with a fumble, the caster may have to relearn or do some sort of penance to regain a spell so that it can be cast again. The specifics per each class are outlined below.
In the standard rules, a wizard is required to prepare the spells that they will cast by memorizing them from out of their spellbook. In the Alternate Casting System, a wizard already knows all the spells in their spellbook and can cast them whenever they choose. However, whenever a spell is attempted to be cast, and a fumble is rolled, the wizard's ability to recall the spell is altered, and they cannot try to cast it again until they rememorize it from out of their spellbook. Rememorizing a spell requires one hour of uninterrupted time for the wizard to rememorize it and cast it again. All fumble checks are made on the Arcane Fumble chart.
Clerics and Warlocks
If a cleric or warlock fumbles while casting a spell, they are barred from that granted spell by their deity or patron until they spend an hour in prayer and or repentance. The actual ritual or task required for this should vary by the deity or patron involved, and the DM and player are encouraged to work out the specifics of it together. Something that the character did has obviously angered their deity or patron in some way, and the fumble and exclusion from the spell are the punishment. Until the time has been spent in prayer or repentance, the cleric or warlock will not be able to cast that particular spell again. All fumble checks are made on the Divine Fumble chart.
A druid that fumbles on a spell roll has become out of balance with the natural world around them from which they draw their ability to cast spells. To re-center themselves, a druid must spend an hour in meditation at the end, which the druid will have repaired the imbalance and be allowed access to that spell to cast once more. Until the hour of re-centering meditation is performed, the druid will not have access to the spell to cast. All fumble checks are made on the Divine Fumble chart.
A paladin that fumbles on a spell-casting roll will need to spend an hour in contemplation, just like a druid, as the failure of the spell is an alert the paladin might be straying from the ideals of their oath. Until the hour of contemplation is performed, the paladin will not be able to cast the spell, which they rolled the fumbled spell-casting check on. All fumble checks are made on the Divine Fumble chart.
Sorcerers, Bards, Rangers
When a sorcerer, bard, or ranger rolls a fumble on a spell-casting check, they will lose the ability to cast that spell again for one hour. Unlike most of the other classes, a sorcerer, bard or ranger has no course of action that needs to be taken besides resting and allowing the internal connection they have to the source of their powers to realign itself with them. Much like a short rest, at least 1 hour must be spent relaxing during which a character does nothing more strenuous than eating, drinking, reading, and tending to wounds. All fumble checks are made on the Arcane Fumble chart.
The Alternate Spell-casting System does not alter or change spell components' necessity if the spell's description calls for them. Each spell's description indicates whether it requires verbal, somatic, or material components. If you can't provide one or more of a spell's components, you cannot cast the spell.
If spell components are material in nature and consumed when the spell is successfully cast, the material component will not be consumed upon a failed spell casting DC check. Material components, however, are consumed when a failed spell-casting check is a fumble.
Spell focuses perform the same way as in traditional 5E spell casting.
The Alternate Casting system does not use spell slots.
Casting in Armor
All rules that that apply for casting magic in armor still apply in the Alternate Spell-casting System.
Cantrips remain unchanged in the Alternate Casting rules and do not require a roll of a spell casting Check when performed.
Ritual spells in the Alternate casting system remain unchanged and still require the same amount of time to perform as they do in traditional 5E casting, and just like cantrips do not require a spell-casting check.
With the Alternate Casting System, all spells are subject to a critical success if a spellcasting check is made, and not just those that require a spell attack roll to hit. If the spell check roll is a natural 20, then the spell becomes supercharged. Damage for a critical success is maxed, and the duration of the spell, its distance, and area of effect are doubled (If the caster wishes it to be) Any material components that were required to cast the spell are also not consumed.
In the Alternate Casting System, there is also a chance to fumble. Fumbles mean that something went wrong with the channeling and directing of the energies that power the magic. If a one is rolled on the D20 when making your spell-casting check, a fumble occurs. The caster is still considered as having taken an action this turn even though the action was a fumble.
A failed spell-casting check will cause the spell to sputter or backfire. A spell that sputters means the energies required to cast it were not collected adequately to cast the spell. The caster can then cast the spell, hoping that they make the spell-casting check the next round or stop their casting of the spell altogether ending it. Rolling a fumble on a spell-casting check means that a backfire has occurred and requires that an additional roll on the backfire table be made. A backfire is when the energies being collected get out of control, causing a result that the caster does not intend to make.
All damage dice rolled in conjunction with a backfire are exploding, meaning that if a dice comes up with the highest result for that die, it is rolled again with the new number being added to the total of damage done. If the next result rolled is again the highest result that can be rolled on that die, you continue rolling until the result is not the highest possible number.
Table: Random Spell Fumble Effect: Arcane
1-2 - The spell sputters for no effect. If material components were needed for the casting of the spell, then they are consumed even if they normally would not be. If using a spell focus, you must wait for one round before being able to use your spell focus again.
3-4 - The spell is cast as normal, but all spell-casting checks for the next minute are done so at a disadvantage.
5-6 - The spell is cast as normal, but the target becomes random. The next closest target, friend or foe, becomes the new target. If this was an area of effect spell and the caster is the area of effect, they too are affected. If the spell was a non-targeted spell, the spell backfires on the caster causing 1d6* psychic damage per level of the spell with a 10ft radius affecting all within that radius. An INT saving throw at the casters DC halves the damage.
7-8 - The spell is cast as normal, but the arcane energy backfires and explodes in a 15ft radius causing 1d8* psychic damage to all within the area of effect. The spell caster is unaffected by this damage, and those caught within the area of effect can roll an INT saving throw at the casters DC to halve the damage.
9-10 - The spell backfires, and the caster takes 1d8* psychic damage per level of the spell. The caster can attempt an INT saving throw at their DC to halve the damage.
11 - The spell sputters, and the caster is unable to caster spells of levels higher than 1st for 1d6 rounds. 1st level spells cast during this time are still subject to a critical fumble.
12 - The spell backfires and explodes in a 15ft radius. All targets within the area of effect, including the caster, will take 1d8* psychic damage with an INT save at casters DC having the damage. In addition, the caster is unable to cast spells above 1st level for 1d6 rounds. 1st level spells cast during this time are still subject to a critical fumble. All material components are consumed, and if the character is using a spell focus, the item becomes useless for 1d6 days.
(*) Dice rolled for damage in a spell fumble are exploding.
NOTE: All spell fumbles include the caster losing the ability to recast the spell which the fumble occurred while casting until they toke the proper steps outlined in their class above to rememorize or attune to the spell once more.
Table: Random Spell Fumble Effect: Divine
1-2 - The spell sputters for no effect as your divine benefactor shows displeasure with you for some past transgression. If material components were needed for the casting of the spell, then they are consumed even if they normally would not be. If using a Holy Symbol was required, you must wait for one round before using your Holy Symbol to cast further spells.
3-4 - The spell is cast as normal, but all future spell casting checks are made at a disadvantage for one minute as you are having trouble channeling the divine energy.
5-6 - The spell is cast as normal, but the target becomes random. The next closest target, friend or foe, becomes the new target. If this was an area of effect spell, and the caster is in the range, they are affected as normal. If the spell was a non-targeted spell, the spell backfires on the caster causing 1d6* radiant (Good), necrotic (Evil), or force (Neutral) damage per level of the spell in a 10ft radius affecting all within the radius. A WIS saving throw at the casters DC halves the damage.
7-8 - The spell is cast as normal, but the Divine energy backfires and explodes in a 15ft radius causing 1d8* radiant (Good), necrotic (Evil), or force (Neutral) damage to all within the area of effect. The spell caster is unaffected by this damage, and those caught within the area of effect can roll a WIS saving throw at the casters DC to halve the damage.
9-10 The spell backfires, and the caster takes 1d8* radiant (Good), necrotic (Evil) or force (Neutral) damage per level of the spell. The caster can attempt a WIS saving throw at their DC to halve the damage.
11 - The spell sputters, and the caster is unable to caster spells of levels higher than 1st for 1d6 rounds. 1st level spells cast during this time as still subject to a critical fumble.
12 - The spell sputters and backfires. All targets within the area of effect, including the caster, will take 1d8* radiant (Good), necrotic (Evil) or force (Neutral) damage. A WIS save at the casters DC halves the damage. In addition, the caster is unable to cast spells above 1st level for 1d6 rounds. 1st level spells cast during this time as still subject to a critical fumble. All material components are consumed, and if the character is using a Holy Symbol, the item becomes useless for 1d6 days in regards to casting further spells.
(*) Dice rolled for damage in a spell fumble are exploding. The type of damage done is determined by the alignment of the god or patron that is bestowing the divine spells. If there is no such being, then damage dealt will be force.
NOTE: If the character loses the ability to use a Holy Symbol to cast spells, and the character can imbue the benefits of a holy symbol into another item, much like a weapon, and were doing so at the time, they lose this ability for the time stated in the fumble. If the same effect is rolled again in another fumble, then the holy symbol becomes ineffective for the new duration.
UPDATE: After posting the article I've gotten a bunch of good feedback and so far everyone thinks that the DC's originally posted were far too low so here is a new version for you guys to try out as well. Let us know what works or what you guys think might work better.