I will go for your skills suggestion number 5. You're right about the Strength being sufficient for climbing should it decide to go for a stroll.
Updating
Mystaran Kraken Working Draft.
Let's go for Triple Standard treasure but maybe note in the flavor that the treasure is mostly in its lair, I guess other than a few (magic) items the kraken might be using.
The original creature's has "G, H" treasure which isn't much better than an AD&D Kraken's "G, R, S (+A)" Considering it's so much more powerful than a Kraken, that implies it's got proportionally less loot – which I guess might be because the Mystaran variety is dimwitted compared to the Genius-level standard Kraken.
So I'm inclined to reduce the amount of treasure and, yes, I'd definitely mention that most of its loot is in its lair.
Maybe "Double Standard (
mostly in lair, only useful magic items will be carried)"?
I think advancement would be good at 65-192HD.
I was fancying 65–96 HD (Colossal) since it's already ginormous enough for me, although I'd be content with the current draft's 65–128 HD.
How likely is it a 192 HD Kraken to see play anyway? At that size it's easier for a DM to just say "too big to harm with ordinary weapons" like some Spelljammer creatures that are treated as scenery or spelljammer ships rather than monsters.
I always have a hard time with epic CRs. What do you think? Low 30s somewhere?
Ugh! I too have a hard time with high-level CRs. The game is just broken at that level (well, it can start breaking down around the teens depending on the classes & gear the PCs can access).
Still, my gut is telling me "high 20s" rather than "low 30s". A simple
freedom of movement spell negates its grappling ability and it doesn't have much else going for it apart from humongous size and damage output.
Put it this way, who would you rather face - this guy or
Khalk'ru? Then consider we gave The Dissolver a CR of 25 after much agonizing debate. A creature that has twelve annihilating tentacle attacks, remember. The Mystaran Kraken seems a teddybear by comparison.
Hmm… did we give The Dissolver a too-low CR? I don't want to go back to that nest of thorns.
Let's see, a normal Kraken is CR 12. Its bigger Mystaran cousin has 52 more HD (+17) and is a size bigger (+1), which'd make him a nice round CR 30. However, he's real stupid and doesn't have any SLAs which might knock off a CR to 29.
That still feels a bit too high to me though, my gut feeling was the big guy's a CR 27 or 28 at most. I tend to guesstimate "big dumb brawler" monsters as being something like 3/5th their Hit Dice at epic levels, since they tend to have several (or many) easily exploitable weaknesses such as a weak Will save and vulnerability to
charm spells or ability damage / energy-draining attacks. (Ability attacks are worse, since it usually has a couple of stats lower than 10 and knocking any of those down to 0 knocks it out of the fight).
2/5th HD for the Mystaran Kraken is CR 25 or 26 by the way, about what Khalk'ru has.