Rebecca

Skill (Cost 0): Yggdrasil Buster:
When Battling with a WOOD elemental character, this character gains 200 ATK

at the start of battle. (Effect last until  end of battle)

Obtainable from:
Free Gacha.

From episode 6 "Can not see the ninja for the Trees" on. as DROP ITEM.

DROP ITEM in event "Subdue The Believer Of Fire!"

By exchanging 100 medals in the Tournament Shop.