Starfield Vocalist

If a permanent entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Warp {1}{U} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Pinnacle Emissary

Whenever you cast an artifact spell, create a 1/1 colorless Drone artifact creature token with flying and "This token can block only creatures with flying."
Warp {U/R} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Frenzied Baloth

This spell can't be countered.
Trample, haste
Creature spells you control can't be countered.
Combat damage can't be prevented.

Steelswarm Operator

Flying
{T}: Add {U}. Spend this mana only to cast an artifact spell.
{T}: Add {U}{U}. Spend this mana only to activate abilities of artifact sources.