special slime

I'm running 1.5.4 on Windows 10 in single player. I combined a Slime Charmer ring with an Iridium Band at the forge. When running the 'Dangerous' mines for Qi, I noticed the stacked slimes, when bounced back at me, would give me a short slime debuff, which the slime charmer ring is supposed to...

for the wizard's large quest (new in 1.5) I've been hunting for a prismatic slime to get that jelly... but the one I found was a special slime, the kind that's guaranteed to drop loot, and instead of the jelly, dropped a glow ring. this was a massive disappoint– i'm not sure i can find another...