Omnath, Locus of Mana

Omnath, der Sammelpunkt des Manas (Omnath, Locus of Mana) (de)

Legendary Creature - Elemental | Power/Toughness: 1 / 1 (CMC 3)
You don't lose unspent green mana as steps and phases end.
Omnath, Locus of Mana gets +1/+1 for each unspent green mana you have.