I understand the need for game balance, but I have long been disappointed that my spell casters can't cast one spell requiring concentration when they have another one cast. One of the most iconic spells for a druid should be barkskin, but my druid never prepared the spell, because casting it would prevent her from casting other spells during the hour she maintained concentration on her barkskin (unless she dropped the barkskin spell, of course).
Wouldn't it be nice if she could cast another spell requiring concentration, while maintaining concentration on the first spell at the same time?
My first thought was to allow a caster to concentrate on a number of spells equal to their constitution modifier, but that leads to the ridiculous scenario where a fighter that takes one level of wizard could concentrate on more spells than a 20th level wizard. I think a better mechanic is just to base it on level. So, a caster could concentrate on a maximum of one spell in their class when their caster level is five or less, but could concentrate on up to two spells when their caster level is between six and ten, three spells between levels eleven and fifteen, and four spells between levels sixteen and twenty.
This does not imply that they could cast multiple spells in a round, but they could cast barkskin, which lasts for an hour, and cast another concentration spell later and have both in effect. If they take damage, they could lose concentration on both spells.
However, this does add power to casters and giving someone both invisibility and fly as a sixth level caster could cause imbalance in the game mechanics, so perhaps other changes are also needed.
I am not sure, but I would really like to be able to have multiple concentration spells in effect at the same time. Do you have ideas for how to make this work?
