Cross is worth 20x and its just x that specific heros power. everything else is normal hero power points. It doesnt x the team as a whole just that specific hero
Cross has 1,000 power and a 20x bonus
Briar has 1,000 power and a 10x bonus
If you took them both, Cross would get 20k points on a win, and Briar would get 10k.
So that’s more than if you just took Cross. The multipliers don’t affect each other, but you get more points for a win. Whether your bonused Heroes make a good, winnable team or not is a strategy decision.