Feeblemind

[Kazuel]

So a situation came up in my game a couple days ago. Long story short, we’re playing a 1 shot at level 20 and the Druid decides to put on a cursed crown that causes him to attack the remaining group. He wildshapes into a mammoth and casts earthquake. I cast feeblemind on him. Feeblemind says he can’t cast spells (he failed the save) and it lowers INT and CHA to 1. Can he maintain concentration on an existing spell and can he continue to wild shape? The DM ruled he could and since it’s a 1 shot it doesn’t really matter but I’m curious what you all think.

[BloodSnake'sCha]

Does the concentration rules say you have to be able to cast spells to keep concentration?


Concentration
Some spells require you to maintain concentration in order to keep their magic active. If you lose concentration, such a spell ends.

If a spell must be maintained with concentration, that fact appears in its Duration entry, and the spell specifies how long you can concentrate on it. You can end concentration at any time (no action required).

Normal activity, such as moving and attacking, doesn't interfere with concentration. The following factors can break concentration:

Casting another spell that requires concentration. You lose concentration on a spell if you cast another spell that requires concentration. You can't concentrate on two spells at once.
Taking damage. Whenever you take damage while you are concentrating on a spell, you must make a Constitution saving throw to maintain your concentration. The DC equals 10 or half the damage you take, whichever number is higher. If you take damage from multiple sources, such as an arrow and a dragon's breath, you make a separate saving throw for each source of damage.
Being incapacitated or killed. You lose concentration on a spell if you are incapacitated or if you die.
The DM might also decide that certain environmental phenomena, such as a wave crashing over you while you're on a storm-tossed ship, require you to succeed on a DC 10 Constitution saving throw to maintain concentration on a spell.


It seems that you don't need the ability to cast spells in order to concentrate on spells.

[JackPhoenix]

Feeblemind doesn't prevents the target from concentrating or end wildshape (or any other active effect, for that matter).

[MrConsideration]

Wild Shape isn't affected by Feeblemind at all.

By RAW nothing says you lose concentration. I would rule active effects continue (Wall of Fire, for example) but any effect needing you to actively direct it would fail (Call Lightning, for example.)