Belzesar's Acute Tarrasquification

Your body takes the characteristics of a Tarrasque. 

You grow to double your size : +100 temporary hit points

Your skin becomes scaly and incredibly tough : +4 to AC

Your muscles swell to double their volume : +5 to Strength (Maxed at 25)

Your body becomes nearly invincible : +5 to Constitution (Maxed at 25)

You become incredibly fast : +40 feet per turn

Your hands become large claws : Claw. Melee Weapon Attack: Add your strength modifier to hit, reach 5 ft, one target. Hit: (4d8 + 10) slashing damage.

You have advantage on saving throws against spells and other magical effects.

You are resistant to Fire, Poison, Bludgeoning, Piercing, and Slashing from Nonmagical Attacks.