Plaxmanta

Flash
When this creature enters, creatures you control gain shroud until end of turn. (They can't be the targets of spells or abilities.)
When this creature enters, sacrifice it unless {G} was spent to cast it.

The List

Commander 2015

Flash
When Plaxmanta enters the battlefield, creatures you control gain shroud until end of turn. (They can't be the targets of spells or abilities.)
When Plaxmanta enters the battlefield, sacrifice it unless {G} was spent to cast it.

Dissension

You may play Plaxmanta any time you could play an instant.
When Plaxmanta comes into play, creatures you control can't be the targets of spells or abilities this turn.
When Plaxmanta comes into play, sacrifice it unless {G} was spent to play it.

If this enters in a way other than announcing it as a spell, then the appropriate mana can't have been paid, and you'll have to sacrifice it.