A common lament at tables I play at from players is often the inherent limitation on being able to maintain concentration on only one spell at a time. This doesn't just come from casters, but also other players wanting to be able to enjoy multiple buff spells at the same time. I find this concern comes up most often during higher-level play where characters generally find themselves having more spells than they are ever likely to use in a day.
In addition, I have found in my own experience playing a sorcerer with a limited spell list that concentration spells are less attractive due to feeling like once I cast one, I can only use the other spells on my list that don't require concentration. This turns an already small list of available spells into an even smaller list.
For the sake of defining parameters, our tables often consist of 4 players creating a balanced group of 2 martial types and 2 caster types. The actual classes chosen are more or less irrelevant to the issue (I think).
The proposed class feature would be added to 11th level for the following caster classes (Bard, Cleric, Druid, Sorcerer, Warlock, and Wizard):
Beginning at 11th level, you may maintain concentration on up to two spells at the same time. Neither spell may be higher than 5th level. If you are required to make a Constitution saving throw to maintain concentration, you must roll separately for each spell you are maintaining concentration on; failure causes you to lose concentration on that spell.
You may also maintain concentration on one spell while readying a second spell. You may not ready a spell while already concentrating on two spells without losing concentration on an existing spell of your choice.
I anticipate that this will make full casters more powerful than they already are, but will also serve to improve the overall power of the party via additional buffing. The increase in power doesn't concern me, but what I am concerned with is whether this opens the door to potentially game-breaking combinations that didn't exist prior to this rule.
The thought process on this was as follows:
- The level requirement is set to more or less make this the domain of dedicated full casters and not the sort of feature that can be acquired by a small level dip. Furthermore, the level selection ensures that levels where spell levels 1-5 see the most action are not diminished by the feature.
- The spell level requirement is set to prevent using 2 extremely powerful concentration spells simultaneously (e.g. no maze AND Otto's irresistible dance at the same time). The in-game threshold on extremely powerful appears to be anything above spell level 5.
- This will open up the known spells list a bit more for spontaneous casters.
- This will generally just make high level play a bit more rocket taggy in nature.
Assuming play at 11th level and higher, would this proposed house rule break the game in a way that couldn't have been done by 2 characters working together in standard RAW?
A good answer would stem from actual experience associated with using a rule like this and what the implications of that were. Recommendations stemming from that experience on how to nerf or buff it to better control the power (limit the spell levels further, increase class restrictions, limit by school, etc.) should also be included.