Sacrificing vs. Protection

[Avodroc20]

Can my opponent make me sacrifice {Emrakul, the Aeons Torn}? It's not being targeted, but since I have no other creatures, do I have to sacrifice Emrakul?

[Kaleo42]

Yes that works.

RESOLVED

[Caboaddict]

Emrakul is a creature like any other, so "sac a creature" applies to him. If an effect require you to sacrifice, bounce, buff, or damage anything, you must do so until either the criteria was met, or no legal options remain.

It's the same reason why a {Simic Growth Chamber} must bounce itself if its controller had other lands on the battlefield when playing it and a {Fiend Hunter} must exile one of its controller's creatures if their opponent had none under their control when he enters the battlefield. Not fun, but must be done.

{fiend hunter} states the player MAY exile a creature. It's not a requirement to exile one of your own creatures when playing fiend hunter and the opponent doesn't have any creatures.