Obsessive Pursuit (Showcase) (TLA-340) [Avatar: The Last Airbender]

When this enchantment enters and at the beginning of your upkeep, you lose 1 life and create a Clue token.

Whenever you attack, put X + 1/1 counters on target attacking creature, where X is the number of permanents you've sacrificed this turn. If X is three or greater, that creature gains lifelink until end of turn.