Gambler's Choice

Signiture Spell
Untap Gambler's Choice on each untap step.
Tap a creature: add a mana of any color
{5}, {t}, Roll a d20 if your result is greater than
the player with the lowest life total. Gain an
emblem that says "Spells you cast gain " Copy
this spell. You may choose new targets for this
spell." Otherwise draw a card."