Sakiko, Mother of Summer

Whenever a creature you control deals combat damage to a player, add that much {G}. Until end of turn, you don't lose this mana as steps and phases end.

Mark of Sakiko

Enchant creature
Enchanted creature has "Whenever this creature deals combat damage to a player, add that much {G}. Until end of turn, you don't lose this mana as steps and phases end."

Brawn

Trample
As long as Brawn is in your graveyard and you control a Forest, creatures you control have trample.

Primal Rage

Creatures you control have trample. (A creature with trample can deal excess combat damage to the player or planeswalker it's attacking.)

Rampaging Brontodon

Trample
Whenever Rampaging Brontodon attacks, it gets +1/+1 until end of turn for each land you control.

Omnath, Locus of Mana

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.

Upwelling

Players don't lose unspent mana as steps and phases end.

Molting Skin

Return Molting Skin to its owner's hand: Regenerate target creature.

Regal Behemoth

Trample
When Regal Behemoth enters the battlefield, you become the monarch.
Whenever you tap a land for mana while you're the monarch, add an additional one mana of any color.