DC on Mimic.

[Tawmis]

So for one to pry their hands free of a Mimic (once they've touched it) - it simply says "Make a DC 13 check" - but doesn't imply what kind of DC - is strength, dexterity, etc?

The obvious choice is "Strength" - but it's odd that it doesn't state it?

Or is it a simple D20, roll 13 or higher, doesn't use any stat?

[firelistener]

It's explicitly stated to be a grapple, so it's the player's choice of Strength (Athletics) or Dexterity (Acrobatics) to escape. See PHB p195 for reference on grappling.

[heavyfuel]

Grapples can be escaped with either a Strength (Athletics) or a Dexterity (Acrobatics) check

Edit: Swordsages don't even exist in 5e and yet here they are!

[Tawmis]

Ah, true! Thank you - even as I read it last night - I didn't even think it was applying to grapple despite the verbiage saying (something to the degree of) to escape the grapple it's at disadvantage my mind took that figuratively last night .... - I was looking for a STR DC 13 or something.

[Farkon]

Just as a reminder, not all mimics are killer mimics and they might just be hungry, so maybe a persuasion check with raw meat on hand could possibly be used to coax the mimic to release your hand.

I had a session where our rogue/sin got caught in a mimic's grasp and our wizard used Prestidigitation to trick the mimic in thinking there was a tastier treat then the rogue and spat out the rogue.

and then we brutally murdered it.

[Tawmis]

Heh - well, for this homebrew I am running them through - there's a whole overall theme of "deception" going on.

They're trapped in the Shadow Vale (similar to Underdark), where the Mountain Dwarves are in the middle of a Civil War amongst each other because of the King.
They encountered a doppleganger that was the best friend of one of the Mountain Dwarves NPC traveling with them - unleashing the doubt of who to trust.
They've encountered monsters (a goblin) who have befriended them and aided them in their quest, which threw them off.
Bullywugs attacked them; but later, the leader confronts them and asks for their aid against the Kuo-Toa.
So throwing in a Mimic to continue to feed that, "Who or what do we even trust is real anymore?" was a fun thing to do.
They're all new to D&D (but were familiar with mimics from other CRPGs and such) - so when I sprang it on them - they were surprised, but all said, "I should have known." :D

This is all building up to a big Drow vs Dwarves war - and they're going about getting allies (so far, Bullywugs, but potential Lizardfolk and Azer).
I had a thread earlier (to try and prep for this all out war) about how folks handle it:
https://forums.giantitp.com/showthread.php?613938-Big-Battles-How-do-you-do-them

[Great Dragon]

Just as a reminder, not all mimics are killer mimics.

True. In the Dragon of Icespire Peak, there is a Talking version of the Mimics.