These are your best bets for creatures to sacrifice, since they can very easily return to play
All of your Dragons, including itself, trigger an enters ability when Scourge is in play to shoot any target for damage equal to the number of Dragons you control
While very common nowadays
Because Jetmir, Nexus of Revels simply has to be on the battlefield to get these buffs, you can keep it in the command zone until youre ready to do some serious damage
Morph is only a cost of two ink, and then he can be used for any character with Shift to be played on top of as if he was the needed card
Notice that the second part, while limited to your first attack, is not limited per player that's to say, if you manage to hit all three of your opponents during your first attack, you get three extra attacks