u/Gullible-Bee-6110

Was wondering on how [[sothera, the supervoid]] first ability works with [[silverquill the disputant]] as i understand it casualty is an additional cost so saccing a creature to casualty is done before the spell is cast and targets are named. So say i double up a [[swords to plowshares]] they shouldnt be able to name the creature they are going to sac to match what i targeted with swords correct? it would have to be a named before i target a creature? Or would i cast and resolve swords and on sothera resolution they would then name what they are saccing? Or am i wrong and they can just name what i targeted? Lol Thanks in advance!