Whenever you add a card that gains Block to your Deck, Enchant it with Nimble 2.
Fresnel Lens currently ranks #4 out of 292 in the Slay the Spire 2 Relics tier list with a rating of 1644.19.
This ranking is based on 29 community votes (25 wins, 4 losses) for a win rate of 86.2%.