Edax Temporis, The Final Dusk

Choose one each turn, it ends at the end of each turn:
• Colorless spells you cast have cascade.
• When tapping a source for mana, add twice that much instead
• You may pay {2}, put a curse counter on target creature.

{1}: Tap target creature.
{3}, {t}: Flicker target creature, activate only as a sorcery
When a creature dies with a curse counter on it, exile it.
You may play Creatures from exile.