Wow, nice 5e presentation and an excellent 5-room-style dungeon! I imagine players will rush into the false tomb after passing the illusion, which means it's a successful diversion! A cue could help pull them back into the prior room, but the DM could easily improvise it.
A few favorite things:
- The Introduction's boxed text! Perfect to just read out to the players!
- The illusion sequence, really clever
- Epic boss battle after the false tomb! With great treasure!
Honestly, this is one of the most usable little dungeons. With a little tinkering with the backstory, I really might drop this into a campaign.