Glowwater Potion is very strong, but early in the run it can be quite difficult to make good use of. Unless you have some cards which gain energy, drawing 10 doesn't actually let you do all that much. In contrast, Fresnel Lens is great to get early in the run, since you still have the entire rest of the run to get offered defensive cards which take advantage of it. I usually take Fresnel Lens here unless I have good energy gain and/or need a potion for an upcoming difficult fight.
You have to give up a lot of max hp to get the lens, but it's quite worth it. Compare 13 hp to 2 hp per block card you play in an act, and you can see that the Lens easily makes up for the health deficit once you add a few blocks. The Lens improves all block generated by a card, so cards that block multiple times like Dodge and Roll or Toric Toughness benefit multiple times from the enchantment. You can get the Fresnel Lens to enchant your defends if you remove and then re-add them with the Pael's Tooth blessing. Since cards can only have one enchantment, the Lens can be a downside if you end up wanting a different enchantment on your block cards.
穿过一片由岩石与静水构成的梦幻之境，你来到了一座散发着逆流光的沉没灯塔前。
你可以把积聚在此的诡异发光水装进瓶子里，或者爬上这座破败的建筑，取下其中的透镜。
装瓶
获得一瓶发光水。
你顺手拿了个瓶子，一边淡定地舀起了那些发光液体，一边看着灯塔安详地沉入了泥沼。
还好你没往里去。
攀爬
获得菲涅耳透镜。失去13点最大生命。
你爬向灯塔顶端，看着它一直稳步下沉，心里直害怕。
进入到灯具室后，你开始着手撬那块透镜，但与此同时那些逆流光正开始榨取你的生命！
最后，你总算把它拧了下来；灯塔也停止了下沉。