Commander Masters

Legendary Creature — Spirit Soldier

Whenever another nontoken creature you control enters, bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Anafenza, Kin-Tree Spirit

Creature — Human Soldier

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.

Elite Scaleguard

March of the Machine Commander

Creature — Human Warrior

Trample
At the beginning of combat on your turn, bolster X, where X is the number of differently named artifact tokens you control. (Choose a creature with the least toughness among creatures you control and put X +1/+1 counters on it.)

Sandsteppe War Riders

Plane — Tarkir

When you planeswalk to The Great Aerie and at the beginning of your upkeep, bolster 3. (Choose a creature with the least toughness among creatures you control and put three +1/+1 counters on it.)
Whenever chaos ensues, choose up to one target creature you control and up to one target creature an opponent controls. Each of those creatures deals damage equal to its toughness to the other.

The Great Aerie

Legendary Artifact — Vehicle

Living metal (During your turn, this Vehicle is also a creature.)
Trample
Whenever you attack, bolster 2. The chosen creature gains trample until end of turn. When that creature deals combat damage to a player this turn, convert Optimus Prime.

Optimus Prime, Autobot Leader

Transformers

Legendary Artifact Creature — Robot

More Than Meets the Eye {2}{U}{R}{W} (You may cast this card converted for {2}{U}{R}{W}.)
At the beginning of each end step, bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)
When Optimus Prime dies, return it to the battlefield converted under its owner's control.

Optimus Prime, Hero

Unfinity Sticker Sheets

Stickers

{TK}{TK} — Whenever this creature attacks, bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)
{TK}{TK}{TK}{TK} — Indestructible
{TK}{TK} — 3/2
{TK}{TK}{TK} — 5/4

Unsanctioned Ancient Juggler

Double Masters 2022

Instant

Bolster 1, then put a +1/+1 counter on each creature you control with a +1/+1 counter on it. (To bolster 1, choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Scale Blessing

The List

Destroy target attacking or blocking creature. Bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Enduring Victory

Sorcery

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Map the Wastes

Destroy target creature with flying. Bolster 2. (Choose a creature with the least toughness among creatures you control and put two +1/+1 counters on it.)

Pinion Feast

Commander 2017

Legendary Creature — Dragon

Flying
Whenever a Dragon you control attacks, bolster 2. (Choose a creature with the least toughness among creatures you control and put two +1/+1 counters on it.)

Dromoka, the Eternal

Dragons of Tarkir

Creature — Bird Soldier

Flying
When this creature enters, bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Aven Tactician

First strike
Whenever this creature attacks, bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Dromoka Captain

Enchantment

{2}{W}: Bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Echoes of the Kin Tree

Enchantment — Aura

Enchant creature
Enchanted creature gets +1/+1 for each +1/+1 counter on other creatures you control.
Enchanted creature has vigilance and "{W}, {T}: Bolster 1." (To bolster 1, choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Gleam of Authority

Creature — Human Wizard

When this creature enters, bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Sandcrafter Mage

Bolster 4. (Choose a creature with the least toughness among creatures you control and put four +1/+1 counters on it.)

Dromoka's Gift

Creature — Dog Scout

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.)

Sandsteppe Scavenger

Bolster X, where X is the number of cards in your hand. Each creature you control with a +1/+1 counter on it gains trample until end of turn. (To bolster X, choose a creature with the least toughness among creatures you control and put X +1/+1 counters on it.)

Sunbringer's Touch

Fate Reforged

Target player sacrifices an enchantment of their choice. Bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Abzan Advantage

Fate Reforged Promos

At the beginning of your end step, bolster X, where X is the number of tapped creatures you control. (Choose a creature with the least toughness among creatures you control and put X +1/+1 counters on it.)

Dragonscale General

Flying
When this creature dies, bolster 2. (Choose a creature with the least toughness among creatures you control and put two +1/+1 counters on it.)

Abzan Skycaptain

You gain 4 life. Bolster 2. (Choose a creature with the least toughness among creatures you control and put two +1/+1 counters on it.)

Honor's Reward

Creature — Elephant

Reach
When this creature enters, bolster 5. (Choose a creature with the least toughness among creatures you control and put five +1/+1 counters on it.)

Sandsteppe Mastodon

Bolster 3. (Choose a creature with the least toughness among creatures you control and put three +1/+1 counters on it.)