Unification a card with an effect used by both player through player selecting a monster level then he most send other different level monster to grave all this must happen during standby phase so there no chance of activating a monster effect that change it level to match others like wind up monsters or deck which have variety in their monsters level like junk ,Dragunity, Dark World, Gusto and spellbook deck 

these deck have difference between boss and searcher plus if you read carefully it says send to grave not destroy giving it a huge boost against negating of destruction card like stardust road , stardust dragon ,etc 

finally this card combined with Mischief of the Yokai  could wipe your opponent field totally  using it from graveyard to decrease the selected monster level by 1 which means all other  monster go directly to graveyard very cool