If Here to Help (from Hidden) plays Fizz, can Fizz play a spell at reaction speed? Can Fizz play cards like Invert Timelines in this scenario?

Ruling: Yes, Fizz can play spells at reaction speed when played by Here to Help, including cards like Invert Timelines. You still have to pay the power costs for any cards played.

Nuances:

• Fizz can even play the same Here to Help that summoned him, since Here to Help fully resolves and goes to the trash before Fizz's triggered ability resolves