After months, maybe years, of training you've honed your skills enough to call on the power of a God. Thor, the God of Thunder, has given you a personal affinity for his own element and allowed you to harness it as a weapon. After spending a full four hour cycle meditating you gain the ability to harness stormy energy. Your fists begin to crackle and give off a blue-ish light. When you make an unarmed melee attack on your enemy, add 4d8 Thunder damage to the attack. In addition, the target must then make a Strength saving throw or be knocked prone.
Using this power granted by Thor has it's consequences however. Once you use this spell, you must make a Constitution saving throw equal to your own spell save DC or become fatigued for 1d4 rounds.
Cast at levels above 5th, add 1d8 to the damage roll.
* - (Mica Chip and Copper Wire)