Omniscience

Omniscience
Class	Watcher
Type	Skill
Rarity	Rare
Cost	4
Effect	Choose a card in your draw pile. Play the chosen card twice and Exhaust it. Exhaust.
Omniscience+
Cost+	3
Effect+	Choose a card in your draw pile. Play the chosen card twice and Exhaust it. Exhaust.

Wishing (omnisciencing?) for an X spell results in the spell being played twice, with X set to your current energy (after accounting for the cost of Omniscience) but not costing you anything (again, other than the cost of Omniscience).

So for example let's say you have 5 energy; you cast Omniscience (costing 4) and choose Brilliance: it will have X=1 and thus you will gain 6hp total (3hp X=1 times, cast twice), with 1 energy left over afterward.