One of my players asked me a interesting question today that I don't have an answer for.
He asked if it is possible to use an action to try and put a sack or bag over a creature's head to prevent that creature from casting spell, and what he would have to roll for?
One use for that would be when fighting a lich to use this to make it impossible for the lich to use spells that require line of sight.
If I make it a contest the lich wouldn't be able to use legendary resistances.
In the following round, the lich would then have to use its action to remove the sack but he proposed that a party could easily cast silent in the meantime and try to grapple the lich making the encounter super easy.
My question is: is that a viable strategy and if so what would you make the player and creature roll?
- A weapon attack with the sack which then has to beat the armor class?
- An ability check for the player and a save for the creature?
- An ability contest?
It would be even more effective when fighting a demilich who doesn't have the arms/hands to remove the bag on his own.