Midnight

Description
Consume all spells and cast them. Consume Midnight.

Only spells left in the deck (uncast since the last shuffle) will be cast and consumed.

Strategy and Synergy
Works well with, which will leave behind a duplicate even after being consumed. It also works well with combined with, since if the Kunais hit, they will replace themselves as well.

Pairs well with a large deck with powerful and expensive spells.

Midnight itself is very expensive, making it very synergistic with things that ensure you have enough mana to cast it, such as Mana Regen, Blue Blood, and Mana Potion.

Take some time before fights to consider what's in your deck so you can have a measured expectation of what Midnight will do before you cast it.