Cool set effects?

Hello, I am a returning player who has been casually playing on and off since launch. This might sound weird to some, but this is my cozy game, its home. I vaguely remember using a set back in the day (monster set?) that summoned a demon or monster to help me when I fought. It was very enjoyable to proc.

My question is : are there more sets that proc special effects or fun things? And is there a place where I could browse them and see what to chase as a long term goal?

Additional info : I’m not into the meta, I dont plan on doing veteran content but rather regular endgame stuff, maybe one day.

Thanks!

Edit : typos