This race would be a little like snowflakes, except that each time you attack someone, you get their bonus for 1 round (The 1 round would continue as long as you attack the same person each turn).
This means if you were to attack a pumpkin, werewolf, frankenstein, and undead on the same turn, as long as you stayed 5 territories big or smaller, you would have a + 15% defense bonus, a +15% attack bonus, a +15% spawn bonus, and your boosts would not disappear if you did not lose a roll in your attack.
When you attack multiple races with contradicting bonuses (e.g. Pumpkins -5% attack & defense bonus, but Franks +15% defense, and Wolves +15% attack) then you gather the good side to each race (e.g. +15% spawn from Pumpkins, +15% attack and defense from Franks and Wolves).