Feat of Resistance

Put a +1/+1 counter on target creature you control. It 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.)

Greatsword of Tyr

Whenever equipped creature attacks, put a +1/+1 counter on it and tap up to one target creature defending player controls.
Equip {W} ({W}: Attach to target creature you control. Equip only as a sorcery.)

Forced Adaptation

Enchant creature
At the beginning of your upkeep, put a +1/+1 counter on enchanted creature.

Ironpaw Aspirant

When Ironpaw Aspirant enters, put a +1/+1 counter on target creature.

Star Pupil

Star Pupil enters with a +1/+1 counter on it.
When Star Pupil dies, put its counters on target creature you control.

Oblivion's Hunger

Target creature you control gains indestructible until end of turn. Draw a card if that creature has a +1/+1 counter on it. (Damage and effects that say "destroy" don't destroy the creature.)

Stony Strength

Put a +1/+1 counter on target creature you control. Untap that creature.

River Heralds' Boon

Put a +1/+1 counter on target creature and a +1/+1 counter on up to one target Merfolk.

Chronicler of Heroes

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

Kenku Artificer

Homunculus Servant — When Kenku Artificer enters, put three +1/+1 counters on up to one target noncreature artifact. That artifact becomes a 0/0 Homunculus artifact creature with flying.

Revelation of Power

Target creature gets +2/+2 until end of turn. If it has a counter on it, it also gains flying and lifelink until end of turn.

Seekers' Squire

When Seekers' Squire enters, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

Unexpected Fangs

Put a +1/+1 counter and a lifelink counter on target creature.

Hunger of the Howlpack

Put a +1/+1 counter on target creature.
Morbid — Put three +1/+1 counters on that creature instead if a creature died this turn.

Wing It

Target creature gets +2/+2 until end of turn. Put a flying counter on it. Scry 1.

Light of Hope

Choose one —
• You gain 4 life.
• Destroy target enchantment.
• Put a +1/+1 counter on target creature.

Shambling Shell

Sacrifice Shambling Shell: Put a +1/+1 counter on target creature.
Dredge 3 (If you would draw a card, you may mill three cards instead. If you do, return this card from your graveyard to your hand.)

Essence Infusion

Put two +1/+1 counters on target creature. It gains lifelink until end of turn.

Parish-Blade Trainee

Training (Whenever this creature attacks with another creature with greater power, put a +1/+1 counter on this creature.)
When Parish-Blade Trainee dies, put its counters on target creature you control.

Gaea's Gift

Put a +1/+1 counter on target creature you control. It gains reach, trample, hexproof, and indestructible until end of turn. (It can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Strength of Solidarity

Choose target creature you control. Put a +1/+1 counter on it for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

Seeker of Sunlight

{2}{G}: Seeker of Sunlight explores. Activate only as a sorcery. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

Boon of Safety

Put a shield counter on target creature. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)
Scry 1.

Mutant's Prey

Target creature you control with a +1/+1 counter on it fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Light the Way

Choose one —
• Put a +1/+1 counter on target creature or Vehicle. Untap it.
• Return target permanent you control to its owner's hand.

Legion Vanguard

{1}, Sacrifice another creature: Legion Vanguard explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

Phantom Interference

Spree (Choose one or more additional costs.)
+ {3} — Create a 2/2 white Spirit creature token with flying.
+ {1} — Counter target spell unless its controller pays {2}.

Pollenbright Druid

When Pollenbright Druid enters, choose one —
• Put a +1/+1 counter on target creature.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Take Up the Shield

Put a +1/+1 counter on target creature. It gains lifelink and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Fallaji Archaeologist

When Fallaji Archaeologist enters, mill three cards. You may put a noncreature, nonland card from among the cards milled this way into your hand. If you don't, put a +1/+1 counter on Fallaji Archaeologist. (To mill a card, put the top card of your library into your graveyard.)

Rubblebelt Maverick

When Rubblebelt Maverick enters, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
{G}, Exile Rubblebelt Maverick from your graveyard: Put a +1/+1 counter on target creature. Activate only as a sorcery.

Servant of the Scale

Servant of the Scale enters with a +1/+1 counter on it.
When Servant of the Scale dies, put X +1/+1 counters on target creature you control, where X is the number of +1/+1 counters on Servant of the Scale.

Jailbreak Scheme

Spree (Choose one or more additional costs.)
+ {3} — Put a +1/+1 counter on target creature. It can't be blocked this turn.
+ {2} — Target artifact or creature's owner puts it on their choice of the top or bottom of their library.

Ent's Fury

Put a +1/+1 counter on target creature you control if its power is 4 or greater. Then that creature gets +1/+1 until end of turn and fights target creature you don't control.

Gift of the Viper

Put a +1/+1 counter, a reach counter, and a deathtouch counter on target creature. Untap it.

Faithful Watchdog

Vigilance
Faithful Watchdog enters with three +1/+1 counters on it.

Travel Preparations

Put a +1/+1 counter on each of up to two target creatures.
Flashback {1}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Courage in Crisis

Put a +1/+1 counter on target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Professor's Warning

Choose one —
• Put a +1/+1 counter on target creature.
• Target creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Guiding Voice

Put a +1/+1 counter on target creature.
Learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)

Snakeskin Veil

Put a +1/+1 counter on target creature you control. It gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

River Herald Scout

When River Herald Scout enters, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

Heir of the Ancient Fang

Heir of the Ancient Fang enters with a +1/+1 counter on it if you control a modified creature. (Equipment, Auras you control, and counters are modifications.)

Arbor Armament

Put a +1/+1 counter on target creature. That creature gains reach until end of turn. (It can block creatures with flying.)

Experiment One

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Remove two +1/+1 counters from Experiment One: Regenerate Experiment One. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Burst of Strength

Put a +1/+1 counter on target creature and untap it.

Ixalli's Diviner

When Ixalli's Diviner enters, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

Guardian Gladewalker

Changeling (This card is every creature type.)
When Guardian Gladewalker enters, put a +1/+1 counter on target creature.

Enduring Bondwarden

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
When this creature dies, put its counters on target creature you control.

Iron Apprentice

Iron Apprentice enters with a +1/+1 counter on it.
When Iron Apprentice dies, if it had counters on it, put those counters on target creature you control.