Fire Emblem is a difficult series, I don't know if you guys have heard

[Words Of Wisdom]

Khuutra said:
Earth supports add +7.5 avoid for every level of support - so at A level it adds 22.5 avoid. If you pair that with Wind, it's 30 for both users. With another Earth, it's 45.

That's the killer right there.  Two earth supports are godly.