"Also going to send this to wherever I can, but I encountered a glitch where I became invincible after equipping the second shield upgrade. Weirdly enough, after any moment of pausing, be it from leveling, chest/tome upgrades, or pause menu, the game will summon a ring of ghost bullets and lightning, causing the game to freeze up. Going to see if I can recreate it by equipping the shield upgrade twice, or if it requires more upgrades to break."