Subterror Behemoth - Hard Control / Stun

A solid deck I built with help of AI and tested it with hand draws and meta bot games. Runs really well.

Extra and Side Deck could be better but I don't really need Extra Deck.

The newest addition is Lord of The Heavenly Prison which apparently is Grade A in my Deck. You can use it at the start of each of your turns and your Face-down cards are indestructible for as much as you want. Or you can trade that destruction immunity for a 3000 ATK / 3000 DEF beater.

Tip: You get Thunder Dragon out with Voltelluric. You can buff him with Terrors in the Hidden City to make him 4100 ATK 4000 DEF(other cards can set him down forcefully so you can flip him up). Will be a lot harder to get rid of and meanwhile your opponent can't search cards from Deck

Tip: Flip Enemy Monsters facedown with Ultramafus then pop them with Stygokraken. They can't protect themselves with Anti-Destruction or Anti-Targeting effects when they are Face-down. They also aren't immune to Ultramafus Flip-down as it's neither targeting nor destruction.

Tip: Pop Enemy backrow with Stygokraken. Use Final Battle beforehand so they wouldn't negate it