The Mimic/Strategies - OSRS Wiki

Upon completion of an elite or master clue scroll, the casket received has a chance of turning out to be a mimic chest. Mimic caskets can only be obtained from an elite or master reward casket after asking the strange casket to enable the chance to obtain a mimic casket (which is disabled by default).

New feature on OSRS Wiki: it can now automatically check off the music tracks you've unlocked : r/2007scape

Tempoross - OSRS Wiki

Oldschool Runescape Mimic Boss

Can I do mimic? : r/2007scape

General Graardor - OSRS Wiki

Holy blessing - OSRS Wiki

TzKal-Zuk - OSRS Wiki

The Mimic adds a little extra reward for you : r/2007scape

Dragon claws - OSRS Wiki

Spindel - OSRS Wiki

Tempoross - OSRS Wiki