Ordeal of Thassa

Enchant creature
Whenever enchanted creature attacks, put a +1/+1 counter on it. Then if it has three or more +1/+1 counters on it, sacrifice Ordeal of Thassa.
When you sacrifice Ordeal of Thassa, draw two cards.

Plains

Akroan Skyguard

Flying
Heroic — Whenever you cast a spell that targets Akroan Skyguard, put a +1/+1 counter on Akroan Skyguard.

Fabled Hero

Double strike
Heroic — Whenever you cast a spell that targets Fabled Hero, put a +1/+1 counter on Fabled Hero.

Hour of Need

Strive — This spell costs {1}{U} more to cast for each target beyond the first.
Exile any number of target creatures. For each creature exiled this way, its controller creates a 4/4 blue Sphinx creature token with flying.

Favored Hoplite

Heroic — Whenever you cast a spell that targets Favored Hoplite, put a +1/+1 counter on Favored Hoplite and prevent all damage that would be dealt to it this turn.

Island

Battlewise Hoplite

Heroic — Whenever you cast a spell that targets Battlewise Hoplite, put a +1/+1 counter on Battlewise Hoplite, then scry 1. (To scry 1, look at the top card of your library, then you may put that card on the bottom.)

Phalanx Formation

Strive — This spell costs {1}{W} more to cast for each target beyond the first.
Any number of target creatures each gain double strike until end of turn. (They deal both first-strike and regular combat damage.)

Launch the Fleet

Strive — This spell costs {1} more to cast for each target beyond the first.
Until end of turn, any number of target creatures each gain "Whenever this creature attacks, create a 1/1 white Soldier creature token that's tapped and attacking."

Gods Willing

Target creature you control gains protection from the color of your choice until end of turn. (It can't be blocked, targeted, dealt damage, enchanted, or equipped by anything of that color.)
Scry 1.

Dawnbringer Charioteers

Flying, lifelink
Heroic — Whenever you cast a spell that targets Dawnbringer Charioteers, put a +1/+1 counter on Dawnbringer Charioteers.

Artful Dodge

Target creature can't be blocked this turn.
Flashback {U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Phalanx Leader

Heroic — Whenever you cast a spell that targets Phalanx Leader, put a +1/+1 counter on each creature you control.

Ajani's Presence

Strive — This spell costs {2}{W} more to cast for each target beyond the first.
Any number of target creatures each get +1/+1 and gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)