Captain America
Ongoing: Your other Ongoing cards here have +2 Power.
Gilgamesh
On Reveal: +1 Power for each of your other cards in play with increased Power.
Lady Sif
On Reveal: Discard the card that costs the most from your hand.
Mister Sinister
On Reveal: Add a Sinister Clone here with the same Power.
Thena
End of Turn: +3 Power if you played (exactly) 2 cards.