Obsidask, Field of Nightmares

{t}, Pay 1 life: Add {b} or {g}
{b}, Pay X life, {t}: Target creature gets -X/-X until end of turn.
{2}{g},{t}: Put the top four cards of your library into your graveyard. You may return a land card from your graveyard to your hand.
{2}{b}{g},{t}: Return target creature card from your graveyard to the battlefield. Activate this ability only if your life total 10 or less.