How are team power levels determined?

1

2

If I remember @Sirrian’s description right from the video:

Troop levels
Troop ascension levels / Rarity
Kingdom Bonuses of the player (include 5* increases)
Gem Masteries

3

Spell does not affect team power?

4

I don’t think so… the magic stat is counted, and I assume the spell power is regulated around the card’s base rarity.