Anafenza, Kin-Tree Spirit

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.)

Sandcrafter Mage

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

Enduring Victory

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.)

Pinion Feast

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.)

Elite Scaleguard

When Elite Scaleguard 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.

Sandsteppe Mastodon

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

Scale Blessing

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.)

Gleam of Authority

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.)

Sunbringer's Touch

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.)

Sandsteppe War Riders

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.)

Echoes of the Kin Tree

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

Cached Defenses

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

Honor's Reward

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.)

Aven Tactician

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

Dromoka's Gift

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

Map the Wastes

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.)

Abzan Skycaptain

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

Dragonscale General

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.)

Abzan Advantage

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.)

Sandsteppe Scavenger

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

Dromoka Captain

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