Elvish Refueler

During your turn, as long as you haven't activated an exhaust ability this turn, you may activate exhaust abilities as though they haven't been activated.
Exhaust — {1}{G}: Put a +1/+1 counter on this creature. (Activate each exhaust ability only once.)

Zirda, the Dawnwaker

Companion — Each permanent card in your starting deck has an activated ability. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
Abilities you activate that aren't mana abilities cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.
{1}, {T}: Target creature can't block this turn.

Loot, the Pathfinder

Double strike, vigilance, haste
Exhaust — {G}, {T}: Add three mana of any one color. (Activate each exhaust ability only once.)
Exhaust — {U}, {T}: Draw three cards.
Exhaust — {R}, {T}: Loot deals 3 damage to any target.

Agatha of the Vile Cauldron

Activated abilities of creatures you control cost {X} less to activate, where X is Agatha's power. This effect can't reduce the mana in that cost to less than one mana.
{4}{R}{G}: Other creatures you control get +1/+1 and gain trample and haste until end of turn.

Sita Varma, Masked Racer

Exhaust — {X}{G}{G}{U}: Put X +1/+1 counters on Sita Varma. Then you may have the base power and toughness of each other creature you control become equal to Sita Varma's power until end of turn. (Activate each exhaust ability only once.)

Rangers' Aetherhive

Vigilance
Whenever you activate an exhaust ability, create a 1/1 colorless Thopter artifact creature token with flying.
Crew 1 (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

Svella, Ice Shaper

{3}, {T}: Create a colorless snow artifact token named Icy Manalith with "{T}: Add one mana of any color."
{6}{R}{G}, {T}: Look at the top four cards of your library. You may cast a spell from among them without paying its mana cost. Put the rest on the bottom of your library in a random order.

Rangers' Refueler

Whenever you activate an exhaust ability, draw a card.
Exhaust — {4}: This Vehicle becomes an artifact creature. Put a +1/+1 counter on it. (Activate each exhaust ability only once.)
Crew 2

Kenrith, the Returned King

{R}: All creatures gain trample and haste until end of turn.
{1}{G}: Put a +1/+1 counter on target creature.
{2}{W}: Target player gains 5 life.
{3}{U}: Target player draws a card.
{4}{B}: Put target creature card from a graveyard onto the battlefield under its owner's control.

Afterburner Expert

Exhaust — {2}{G}{G}: Put two +1/+1 counters on this creature. (Activate each exhaust ability only once.)
Whenever you activate an exhaust ability, return this card from your graveyard to the battlefield.

Eldrazi Displacer

Devoid (This card has no color.)
{2}{C}: Exile another target creature, then return it to the battlefield tapped under its owner's control. ({C} represents colorless mana.)

Chulane, Teller of Tales

Vigilance
Whenever you cast a creature spell, draw a card, then you may put a land card from your hand onto the battlefield.
{3}, {T}: Return target creature you control to its owner's hand.

Boom Scholar

Exhaust abilities of other permanents you control cost {2} less to activate.
Exhaust — {4}{R}{G}: Creatures and Vehicles you control gain trample until end of turn. Put two +1/+1 counters on this creature. (Activate each exhaust ability only once.)

Mindspring Merfolk

Exhaust — {X}{U}{U}, {T}: Draw X cards. Put a +1/+1 counter on each Merfolk creature you control. (Activate each exhaust ability only once.)

Greenbelt Guardian

{G}: Target creature gains trample until end of turn.
Exhaust — {3}{G}: Put three +1/+1 counters on this creature. (Activate each exhaust ability only once.)

Emiel the Blessed

{3}: Exile another target creature you control, then return it to the battlefield under its owner's control.
Whenever another creature you control enters, you may pay {G/W}. If you do, put a +1/+1 counter on it. If it's a Unicorn, put two +1/+1 counters on it instead. ({G/W} can be paid with either {G} or {W}.)

Skyserpent Seeker

Flying, deathtouch
Exhaust — {4}: Reveal cards from the top of your library until you reveal two land cards. Put those land cards onto the battlefield tapped and the rest on the bottom of your library in a random order. Put a +1/+1 counter on this creature. (Activate each exhaust ability only once.)

Gilraen, Dúnedain Protector

{2}, {T}: Exile another target creature you control. You may return that card to the battlefield under its owner's control. If you don't, at the beginning of the next end step, return that card to the battlefield under its owner's control with a vigilance counter and a lifelink counter on it.

Redshift, Rocketeer Chief

Vigilance
{T}: Add X mana of any one color, where X is Redshift's power. Spend this mana only to activate abilities.
Exhaust — {10}{R}{G}: Put any number of permanent cards from your hand onto the battlefield. (Activate each exhaust ability only once.)

Biomancer's Familiar

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.
{T}: The next time target creature adapts this turn, it adapts as though it had no +1/+1 counters on it.

Agatha's Soul Cauldron

You may spend mana as though it were mana of any color to activate abilities of creatures you control.
Creatures you control with +1/+1 counters on them have all activated abilities of all creature cards exiled with Agatha's Soul Cauldron.
{T}: Exile target card from a graveyard. When a creature card is exiled this way, put a +1/+1 counter on target creature you control.

Draconautics Engineer

Exhaust — {R}: Other creatures you control gain haste until end of turn. Put a +1/+1 counter on this creature. (Activate each exhaust ability only once.)
Exhaust — {3}{R}: Create a 4/4 red Dinosaur Dragon creature token with flying.

Boommobile

When this Vehicle enters, add four mana of any one color. Spend this mana only to activate abilities.
Exhaust — {X}{2}{R}: This Vehicle deals X damage to any target. Put a +1/+1 counter on this Vehicle. (Activate each exhaust ability only once.)
Crew 2