Alter Ego Have a base damage multiplier of 1.0x.
Rider, Caster and Assassin take 50% more damage from Alter-Ego.
Saber, Archer and Lancer take half damage from Alter-Ego.
Berserkers take double damage from Alter Ego and deal 50% extra damage against them.
Beast III/R take 20% more damage from Alter-Ego.