Lofura, the Impossible Form

Hexproof, indestructible
Whenever an opponent draws a card, he or she reveals it and chooses a creature you control. Put X +1/+1 counters on the chosen creature, where X is the revealed card's converted mana cost.
{t}: Each player draws a card.
Lofura can't attack or block unless it has a +1/+1 counter on it.