"Lava is blinding me." Solution: Open the Xray pack zip. Find assets/minecraft/textures/blocks/lava_still.png and lava_flow.png . Replace them with a 16x16 transparent pink image.
"The Xray works, but I can't see caves." Solution: That is the point. Xray removes stone so you see ores floating in a void. You do not see caves; you see straight through the world. To see caves, hold a torch (the light update will show you cave walls). Conclusion: Is the Minecraft 1.12 Xray Texture Pack Worth It? If you are playing on a competitive server where bans have real consequences (lost ranks, lost items), no —the risk outweighs the reward. minecraft 1.12 xray texture pack
Happy (and transparent) mining.