I would like opening chests to have a small chance of spawning a pack of monsters

Regular chests - regular pack

Blue chests - magic pack

Yellow chests - rare pack

The chests would still drop their loot, just give an added bonus of more monsters and potentially even more drops from killing the pack.

tl;dr: Turn chests into mimic-like encounters so there is a bit more spice when clicking them. That is all. Thank you.