Snecko eye is damn fun. It randomizes the costs of the cards in your hand to somewhere in the range of [0,3], which is terrible if you're running low cost cards, but amazing if you're running heavy cards. I picked it up as my first boss relic and promptly through my careful strategy of a wall of flame/thorns deck to the wind and just opted to pick up basically any card with a cost greater than or equal to 2, with a few special mentions I kept an eye out for; dual wielding chief among them.
Dual wielding is a lovely card that gives you a copy (two copies when upgraded) of any attack or power card in your hand. The fun thing about it, is it copies the card at its current cost, not its actual cost. So, running snecko eye, you can get some crazy combos. Bludgeon, for instance, is normally a massive damage card that costs three, so snecko eye gives it a 75% chance to come into play at reduced cost. If you're lucky and it comes into play at cost 0, and you have a dual wield that you can cast, that gives you three massive damage cards that you can cast basically at the cost of the dual wield.
Took some damage, and the run could easily have ended with one stroke of bad luck, but I scored my second win on the final boss. Snecko eye is wacky fun.
Slay the Spire, again.