Hunter's Nightmare

When Hunters Nightmare Enters the Battlefield
add {c}.
At the beginning of each end step you may pay
1 life, if you do target opponent Unveils 1. (That
player reveals an unrevealed card from their hand. If
a land card is revealed this way they lose 1 life.
{t} Add one mana of any colour. Activate only if
all cards in an opponents hand are revealed to
you.