Aaaaaaand there's my first Watcher victory over the Spire, against Clock Bastard - after only 16 deaths, which is way quicker than any other character.
Bit jammy - what won it was really:
Sacred Bark Boss relic. This doubles the effectiveness of potions.
Cultist potion, bought at the final shop. Thus gives you a +1 strength escalator per turn. Ah, but remember that Sacred Bark? So, +2. Demon Form in potion guise, so 0 cost.
Nilry's Codex Event Relic. Choose 1 of 3 cards to shuffle into your draw pile at the end of your turn. So I could cherry pick a ton of gold cards, powers and the like.
Other good stuff?
Deva Form is a mana escalator - Scrawl gives you the cards to spend it on.
I had three Vault+ at the end, which are awesome. Gives you an extra turn, so reset mana, draw five cards, trip your escalators, choose a new card with Nildry, and not have to drop out of Wrath.
And a Signature Move, which gives huge damage if you can clear the other attacks - again, Deva Form allows you to cast them to get them out of the way.
Once she's rolling, she's a damage machine. Not sure I'd have beaten the Enlightened One.