mtg.wtf

Remove a +1/+1 counter from Arcbound Reclaimer: Put target artifact card from your graveyard on top of your library.
Modular 2

First strike
When Arcbound Shikari enters the battlefield, put a +1/+1 counter on each other artifact creature you control.
Modular 2

Modular 4
Riot

Whenever Arcbound Slith deals combat damage to a player, put a +1/+1 counter on it.
Modular 1

Flying
Modular 1

Menace
Modular 2
Whenever you cast a spell other than your first spell each turn, put a +1/+1 counter on Arcbound Tracker.

Modular—Sunburst

Flying
{R}: Arcbound Whelp gets +1/+0 until end of turn.
Modular 2

Modular 1

Living metal
Whenever you cast a spell that targets one or more creatures or Vehicles you control, put that many +1/+1 counters on Arcee. Convert Arcee.

More Than Meets the Eye {R}{W}
First strike
{1}, Remove one or more +1/+1 counters from Arcee: It deals that much damage to target creature. Convert Arcee.

When Archaeomancer's Map enters the battlefield, search your library for up to two basic Plains cards, reveal them, put them into your hand, then shuffle.
Whenever a land enters the battlefield under an opponent's control, if that player controls more lands than you, you may put a land card from your hand onto the battlefield.

Flash
Flying, vigilance
When Archangel Avacyn enters the battlefield, creatures you control gain indestructible until end of turn.
When a non-Angel creature you control dies, transform Archangel Avacyn at the beginning of the next upkeep.

[+1]: Create a 1/1 white Soldier creature token with lifelink.
[–2]: Put two +1/+1 counters on target creature. It becomes an Angel in addition to its other types and gains flying.
[–6]: Return all nonland permanent cards with mana value 3 or less from your graveyard to the battlefield.

As long as Archelos, Lagoon Mystic is tapped, other permanents enter the battlefield tapped.
As long as Archelos is untapped, other permanents enter the battlefield untapped.

When Architects of Will enters the battlefield, look at the top three cards of target player's library, then put them back in any order.
Cycling {U/B}

{T}: Target artifact creature's controller sacrifices it. That player may search their library for a noncreature artifact card, put it onto the battlefield, then shuffle.

When Arcum's Astrolabe enters the battlefield, draw a card.
{1}, {T}: Add one mana of any color.

{2}, {T}: Target creature gains vigilance until end of turn. Activate only during combat and only if defending player controls a snow land.

{2}, {T}: Target snow land is no longer snow.
{2}, {T}: Target nonsnow basic land becomes snow.

{3}, {T}: Choose target non-Wall creature the active player has controlled continuously since the beginning of the turn. That player may pay {X}, where X is that mana value. If they don't pay, the creature attacks this turn if able, and at the beginning of the next end step, destroy it if it didn't attack this turn. Activate only before attackers are declared.

At the beginning of combat on your turn, you may attach any number of Auras and Equipment you control to target permanent or player.
Partner

Haste
Whenever Ardoz, Cobbler of War or another creature enters the battlefield under your control, that creature gets +2/+0 until end of turn.
{3}{R}: Create a 1/1 red Goblin creature token with haste. Activate only as a sorcery.

Starting intensity 0
Whenever another creature enters the battlefield under your control, perpetually increase the intensity of Arek and the intensity of all cards named Arek, False Goldwarden in your graveyard, hand, and library by 1.
{3}{W}{B}, {T}, Sacrifice Arek: Target opponent loses X life and you gain X life, where X is Arek's intensity.

Legendary creatures don't untap during their controllers' untap steps.
When Arena of the Ancients enters the battlefield, tap all legendary creatures.