I love how you used the theme. Making each attack get weaker as you use them but buff the other attack is a great idea to encourage the player to vary their playstyle. The game also has great art.
Unfortunately, there is a bit of chunkiness to the game. Having to use up to jump is annoying. Spacebar is much more of a standard jump button. Additionally, the audio balance isn't great. The music is very quiet compared to the sound effects unfortunately. Additionally, it's too easy to sit back and use the lightning bolts against some enemies, even at 10% effectiveness.
I don't want this to make it sound like I disliked the game though. It's quite amazing for being made in 7 days. I've only seen this kind of mechanic present in the game Salt and Sanctuary before. In there, there are fire and electric spells. Using spells of one kind will "imbalance" you. Continuing to use the same element will eventually cause you to explode unless you wait or use the other element. IA similar mechanic is used to great effect here and I like that taking damage also boosts you damage. It make getting hit feel way less bad. It helps the player fail forward so they stick with their mistake and move forward.
Overall, the game has some amazing ideas and I'd love to see where it can go with some polish.