Solidarity of Heroes

Strive — This spell costs {1}{G} more to cast for each target beyond the first.
Choose any number of target creatures. Double the number of +1/+1 counters on each of them.

Karametra, God of Harvests

Indestructible
As long as your devotion to green and white is less than seven, Karametra isn't a creature.
Whenever you cast a creature spell, you may search your library for a Forest or Plains card, put it onto the battlefield tapped, then shuffle.

Chronicler of Heroes

When Chronicler of Heroes enters, draw a card if you control a creature with a +1/+1 counter on it.

Reap What Is Sown

Put a +1/+1 counter on each of up to three target creatures.

Calix, Destiny's Hand

+1: Look at the top four cards of your library. You may reveal an enchantment card from among them and put that card into your hand. Put the rest on the bottom of your library in a random order.
−3: Exile target creature or enchantment you don't control until target enchantment you control leaves the battlefield.
−7: Return all enchantment cards from your graveyard to the battlefield.

Siona, Captain of the Pyleas

When Siona, Captain of the Pyleas enters, look at the top seven cards of your library. You may reveal an Aura card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Whenever an Aura you control becomes attached to a creature you control, create a 1/1 white Human Soldier creature token.

Ajani, Mentor of Heroes

+1: Distribute three +1/+1 counters among one, two, or three target creatures you control.
+1: Look at the top four cards of your library. You may reveal an Aura, creature, or planeswalker card from among them and put it into your hand. Put the rest on the bottom of your library in any order.
−8: You gain 100 life.

Bronzehide Lion

{G}{W}: Bronzehide Lion gains indestructible until end of turn.
When Bronzehide Lion dies, return it to the battlefield. It's an Aura enchantment with enchant creature you control and "{G}{W}: Enchanted creature gains indestructible until end of turn," and it loses all other abilities.

Hero of Iroas

Aura spells you cast cost {1} less to cast.
Heroic — Whenever you cast a spell that targets Hero of Iroas, put a +1/+1 counter on Hero of Iroas.

Fleecemane Lion

{3}{G}{W}: Monstrosity 1. (If this creature isn't monstrous, put a +1/+1 counter on it and it becomes monstrous.)
As long as Fleecemane Lion is monstrous, it has hexproof and indestructible.