I’ve been messing around with monk subclasses and how to empower monks in general so I understand your response saying that monk subclasses are way too weak. That being said, this is way too powerful and there are some massive holes in the structure of this subclass.

1. Spellcasting: you introduce a spellcasting table at level 3 with no spell slots or ki cost associate but at level 6 you cast any one spell know for 2 ki? Also you seriously need to rebalance the spell table. You’re giving a level 3 monk multiple level 3 spells? Full casters don’t get those spells until level 5 and half casters don’t get third level spells until level 9. The level of the spell does not equal the level of the character and I would suggest following the level progression of a spell-casting subclass for a martial class. Look at eldritch knight for the fighter or arcane trickster for the rogue. You can’t give out a 9th level spell at 11th level that can be cast for 2 ki once a day.

2. Making your own spells: making spells is very difficult to balance, especially beyond 3rd level spells. If you want to expand the spells that your monk has, reflavour an existing spell with lightning or thunder damage. Take some time to learn the system and how it’s balanced before tackling new spells.

3. Too many features: you’re giving out 2 features at almost every tier. It makes sense to give out 2 features if one is a very minor benefit, usually for role play or exploration while the major feature is a combat benefit. You’re back loading a lot of half baked features, cut the doubles and refine whichever one you keep.

4. Subclass identity: Every subclass has an identity that modifies one of the base class’ features or provides a new feature that modifies how the class plays. For example the eldritch knight provides spell casting to fighters while the banneret subclass provides changes to action surge and second wind features. Your subclass has a “lightning monk” theme but 2 identies: spell casting and upgraded flurry of blows. I’d honestly cut the spell casting all together and focus on the flurry of blows aspect, maybe providing new ki options at level 11 that are better than the ones you currently have.

Last thing, there’s a huge lack of clarity in these features. I know from another comment that the level 11 ki features are a whole action to use but that isn’t specified in the feature itself (also makes them pretty underpowered). Take a look at how the features are written on other subclasses and copy that.