Mod explanations in the comments, turn: Team Tweak

Triplekill: Shoot three different teams
Sacrifice: You have the option to sacrifice one life (=gain an X), but if your shot hits, it instakills the team you choose.

Note: For every life you sacrifice, you have the chance to instakill ONE team. Meaning for an instakill chance of every team, you have to sacrifice three lives.

Can triple kill and sacrifice be used together at once?

Yes (because there is a mod that makes the turn have two mods)
But like I said: For every life you sacrifice, you have the chance to instakill ONE team. Meaning for an instakill chance of every team, you have to sacrifice three lives.