Memento Mori

Creatures do not regenerate any toughness after combat. Players cannot regenerate any health.
{b}: Each player must sacrifice the creature with the highest converted mana cost or lose health equal to half that creature's converted mana cost.
{5} All creatures with any +1+1 counters on them are sacrificed.
{t} exile any creature that has taken damage last turn. If you use this ability, you must sacrifice a creature with equal or higher converted mana cost.

Remember death.