Hello everyone and welcome to my 207th analysis, this time featuring Cryotan.
Overview: When you look at his stats, you'll think Cryotan should definitely be a tank that functions in a similar way to Ouros; staying alive and killing enemies off by the Death Counter of Euboea, a Mega Freeze move that sets the target on a 3 turn Death Counter, effectively giving them 1 turn to move without other monsters' interception. Coupled with his Mountain trait allowing him to protect himself from some of the most common deny methods, you have yourself a monster who's difficult to keep down. While stall is a plausible strategy - and at times will be the go-to move to utilize - the true power of Cryotan lies in the move Boösaule Montes. This move Mega Freezes the entire enemy team, and with the insane power level of Monsters nowadays, 2 turns is more than enough to greatly dismantle, or even kill, the enemy team. An AOE deny move like this might suggest a fast denier style, but this is an incorrect deduction since Boösaule Montes has a Stamina cost of 250, which necessitates the usage of Stamina Runes, which in turn prevents him from running 3 Speed Runes (there is a way to remedy this, but I'll get into that later, plus it is situational). Thus, the better way(usually) to use Cryotan is as something like a tanky secondary denier: Mega Freezing the enemy team with Boösaule Montes while dealing with pesky monsters using Euboea, and giving yourself Taunt if need be, though stall always remains an option especially against Possession-heavy teams.

-Boösaule Montes/Elysium
Runes: 1 Stamina (at least Level V) 1 Speed 1 Life or 2 Stamina 1 Life (if you have runes at Level IV or below)/ 2 Life 1 Speed
Mutant Rune options: Speed&Life, Stamina&Speed, Life&Speed
Relics: Armors and Traps

Build Explanation:
Boösaule Montes is a pivotal move in Cryotan's arsenal since it allows him to excellently perform the role of secondary denier. Skadi allows him to do something after Boösaule Montes has been used - you will almost always have enough Stamina to use any of your other moves after using this, not to mention it gives the AI a way out of Possession. Euboea puts tough enemies like Ouros on a Death Timer, and if they are able to be Mega Frozen, this will give them just 1 turn to move. Lastly, Olympus allows Cryotan to function as a tank by receiving all single target moves and essentially doubling his Life. Alternatively, a stall based approach can be used by forgoing Boösaule Montes in the first slot for Elysium. This gives Cryotan a better shot at dealing with Possession monsters and capitalizes more on his tank role by making him ridiculously hard to kill when combined with Olympus (essentially giving you a 200% Life Shield), and this moveset can be used if the attack target has many monsters that can deal with Freeze effects or you feel like the battle will be a stall war, which is a battle Cryotan will almost always win.
For the Boösaule Montes set, 1 Stamina, Speed and Life will give him enough Stamina to use said move (if your Stamina Rune is at least Level V), make him not too slow and improve the power of Olympus. If your Runes are low leveled, you'd have to go with 2 Stamina 1 Life. The Elysium set instead utilizes 2 Life 1 Speed, which makes Cryotan extremely tanky. As for Mutant Runes, they focus on getting as much extra Life and Speed as possible.

Team Options: AOE CD Deactivators like Captain Copperbeard can be used to deactivate the CDs of all allies: with Skadi and Euboea, Cryotan can target all enemies one by one each time he gets a turn this way - Captain Copperbeard can also be a primary denier with his AOE Stun. For more Teammate options, check out this article.

Countering Cryotan: Removing debuffs from your team saves the target of Euboea. If you get lucky with Possession, both Euboea and especially Boösaule Montes will have devastating effects on Cryotan's team. For more Counter options, check out this article.