Joshua, Secret Santa

{1}{r}{g}Secret—(From your hand, you can put this card secretly underneath any card. Once per turn, you may move it to another card. If it get's noticed by a player and they point it out; you must pay it's secret cost at the beginning of your next upkeep. If you can't, you lose the game.)
When this card is noticed by an opponent, you gain X life and each opponent decays- uh, I mean sacrifices X lands. X is the amount of cards, this card was und