Great use for Lizgoth spines
Lizgoth spines are used to craft one item, and the majority of them go to waste.
I suggest adding a Bounty Collector NPC with the NPC who assembles lizard maps, and this NPC would trade Reptile Slayer and Lizgoth Slayer weapons in exchange for Lizgoth spines and Lizgoth eggs. Regular weapons that roll with a guaranteed Reptile of Lizgoth slayer mod.
Possibly, allow the chance to roll and additional random slayer mod for alternatives to artifact gear.
If you want to include artifacts as a trade in reward, make them lesser artifacts. This will help people get started with the lizard map content, and you can't have the items you get at the beginning be better than the ones you get at the end.
A similar NPC to trade Spider and Arachnid Slayer weapons would work as well. With so many spider dungeons in the game, and so many interesting but useless drops (spider eyes, sulfur rocks, frozen webs, spider keys)
Turning in those useless items for slayer weapons would add a nice layer of content to the game.