So, I was playing against a friend and couldn't figure out how this played out...
A card:Geth's Verdict was played and the only creature that could be sacrificed was Mirran Crusader. Now I know it couldnt be targeted by the black spell, however since it went through the player, does it force the sac?
Yes. The Verdict targets you, and you choose the creature to sac. Since it's not targeting the Crusader, the protection doesn't stop the sacrifice.
114.9a Just because an object or player is being affected by a spell or ability doesnt make that object or player a target of that spell or ability. Unless that object or player is identified by the word "target" in the text of that spell or ability, or the rule for that keyword ability, its not a target.
Since card:Geth's Verdict doesn't target the creature, it doesn't matter if that creature has protection from it. It targets a player, and that player sacrifices a creature.
the verdict targets the player not the creature
as long as the spell or effect causing the sack does not use the word target, the creature must be sacked
a sack spell that does say sack target creature can not be played on creatures with protection from it because its not a legal target
further more if there are no other creatures for a target creature spell you can not even play it and put it onto the stack to fizzel
you must have a legal target for a spell or ability to play or activate it,
if there are no legal targets you cant play it even if your going to need to discard it and would activate some other ability for playing it