Pollenbright Druid

When this creature 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.)

Mikaeus, the Lunarch

Mikaeus enters with X +1/+1 counters on it.
{T}: Put a +1/+1 counter on Mikaeus.
{T}, Remove a +1/+1 counter from Mikaeus: Put a +1/+1 counter on each other creature you control.

Unruly Mob

Whenever another creature you control dies, put a +1/+1 counter on this creature.

Sigarda's Summons

Creatures you control with +1/+1 counters on them have base power and toughness 4/4, have flying, and are Angels in addition to their other types.

Lae'zel, Vlaakith's Champion

If you would put one or more counters on a creature or planeswalker you control or on yourself, put that many plus one of each of those kinds of counters on that permanent or player instead.
Choose a Background (You can have a Background as a second commander.)

Overwhelming Encounter

Creatures you control gain vigilance and trample until end of turn. Roll a d20.
1—9 | Creatures you control get +2/+2 until end of turn.
10—19 | Put two +1/+1 counters on each creature you control.
20 | Put four +1/+1 counters on each creature you control.

Cloakwood Swarmkeeper

Gathered Swarm — Whenever one or more tokens you control enter, put a +1/+1 counter on this creature.

Song of Freyalise

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Until your next turn, creatures you control gain "{T}: Add one mana of any color."
III — Put a +1/+1 counter on each creature you control. Those creatures gain vigilance, trample, and indestructible until end of turn.

Cadira, Caller of the Small

Trample
Whenever Cadira deals combat damage to a player, for each token you control, create a 1/1 white Rabbit creature token.

Conclave Mentor

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on that creature instead.
When this creature dies, you gain life equal to its power.

Orochi Merge-Keeper

{T}: Add {G}.
As long as this creature is modified, it has "{T}: Add {G}{G}." (Equipment, Auras you control, and counters are modifications.)

Recruitment Drive

Roll a d20.
1—9 | Create two 1/1 white Soldier creature tokens.
10—19 | Create two 2/2 white Knight creature tokens.
20 | Create three 2/2 white Knight creature tokens.

Forest

Iridescent Hornbeetle

At the beginning of your end step, create a 1/1 green Insect creature token for each +1/+1 counter you've put on creatures under your control this turn.

Sigardian Paladin

As long as you've put one or more +1/+1 counters on a creature this turn, this creature has trample and lifelink.
{1}{G}{W}: Target creature you control with a +1/+1 counter on it gains trample and lifelink until end of turn.

Elite Scaleguard

When this creature enters, bolster 2. (Choose a creature with the least toughness among creatures you control and put two +1/+1 counters on it.)
Whenever a creature you control with a +1/+1 counter on it attacks, tap target creature defending player controls.

Master Chef

Commander creatures you own have "This creature enters with an additional +1/+1 counter on it" and "Other creatures you control enter with an additional +1/+1 counter on them."

Gluntch, the Bestower

Flying
At the beginning of your end step, choose a player. They put two +1/+1 counters on a creature they control. Choose a second player to draw a card. Then choose a third player to create two Treasure tokens.

Angelic Sleuth

Flying
Whenever another permanent you control leaves the battlefield, if it had counters on it, investigate. (Create a Clue artifact token with "{2}, Sacrifice this token: Draw a card.")

Nantuko Cultivator

When this creature enters, you may discard any number of land cards. Put that many +1/+1 counters on this creature and draw that many cards.

Unbounded Potential

Choose one —
• Put a +1/+1 counter on each of up to two target creatures.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Entwine {3}{W} (Choose both if you pay the entwine cost.)

Sigil Blessing

Until end of turn, target creature you control gets +3/+3 and other creatures you control get +1/+1.

Odric's Outrider

Whenever this creature or another creature you control dies, put a +1/+1 counter on target creature you control.

Celebrity Fencer

Alliance — Whenever another creature you control enters, put a +1/+1 counter on this creature.

Abzan Battle Priest

Outlast {W} ({W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has lifelink.

Plaguemaw Beast

{T}, Sacrifice a creature: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Ironshell Beetle

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

Felidar Retreat

Landfall — Whenever a land you control enters, choose one —
• Create a 2/2 white Cat Beast creature token.
• Put a +1/+1 counter on each creature you control. Those creatures gain vigilance until end of turn.

Backup Agent

Tempered Veteran

{W}, {T}: Put a +1/+1 counter on target creature with a +1/+1 counter on it.
{4}{W}{W}, {T}: Put a +1/+1 counter on target creature.

Shanna, Sisay's Legacy

Shanna can't be the target of abilities your opponents control.
Shanna gets +1/+1 for each creature you control.

Noble Heritage

Commander creatures you own have "When this creature enters and at the beginning of your upkeep, each player may put two +1/+1 counters on a creature they control. For each opponent who does, you gain protection from that player until your next turn." (You can't be targeted, dealt damage, or enchanted by anything controlled by that player.)

Duskshell Crawler

When this creature enters, put a +1/+1 counter on target creature.
Each creature you control with a +1/+1 counter on it has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Botanical Plaza

This land enters tapped.
{T}: Add {G} or {W}.
{2}{G}{W}, {T}, Sacrifice this land: Draw a card.

Undercellar Myconid

Whenever this creature enters or dies, create a 1/1 green Saproling creature token.
{T}: Add one mana of any color.

Mage's Attendant

When this creature enters, create a 1/1 blue Wizard creature token with "{1}, Sacrifice this token: Counter target noncreature spell unless its controller pays {1}."

Vitu-Ghazi, the City-Tree

{T}: Add {C}.
{2}{G}{W}, {T}: Create a 1/1 green Saproling creature token.

Drillworks Mole

{2}, {T}: Put a +1/+1 counter on this creature and a +1/+1 counter on up to one target commander creature you control.

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.)

Paradise Druid

This creature has hexproof as long as it's untapped. (It can't be the target of spells or abilities your opponents control.)
{T}: Add one mana of any color.

Wildwood Scourge

This creature enters with X +1/+1 counters on it.
Whenever one or more +1/+1 counters are put on another non-Hydra creature you control, put a +1/+1 counter on this creature.

Slith Ascendant

Flying
Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.

Plains

Heir of the Ancient Fang

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

Carefree Swinemaster

Whenever this creature attacks, you may pay {1}{G}. If you do, create a 2/2 green Boar creature token that's tapped and attacking.

Mowu, Loyal Companion

Vigilance, trample
If one or more +1/+1 counters would be put on Mowu, that many plus one +1/+1 counters are put on it instead.

Rishkar, Peema Renegade

When Rishkar enters, put a +1/+1 counter on each of up to two target creatures.
Each creature you control with a counter on it has "{T}: Add {G}."

Ambitious Dragonborn

This creature enters with X +1/+1 counters on it, where X is the greatest power among creatures you control and creature cards in your graveyard.

Safehold Elite

Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Towashi Guide-Bot

When this creature enters, put a +1/+1 counter on target creature you control.
{4}, {T}: Draw a card. This ability costs {1} less to activate for each modified creature you control. (Equipment, Auras you control, and counters are modifications.)

Orzhov Advokist

At the beginning of your upkeep, each player may put two +1/+1 counters on a creature they control. If a player does, creatures that player controls can't attack you or planeswalkers you control until your next turn.

Inspiring Call

Draw a card for each creature you control with a +1/+1 counter on it. Those creatures gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Githzerai Monk

Flash
Flying
Psychic Defense — When this creature enters, tap all creatures you don't control.

Holdout Settlement

{T}: Add {C}. ({C} represents colorless mana.)
{T}, Tap an untapped creature you control: Add one mana of any color.