Have

Vigean Hydropon

Graft 5 (This creature enters with five +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
Vigean Hydropon can't attack or block.

Captured by Lagacs

Enchant creature
Enchanted creature can't attack or block.
When Captured by Lagacs enters, support 2. (Put a +1/+1 counter on each of up to two target creatures.)

Reap What Is Sown

Put a +1/+1 counter on each of up to three target creatures.

Simic Basilisk

Graft 3 (This creature enters with three +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{1}{G}: Until end of turn, target creature with a +1/+1 counter on it gains "Whenever this creature deals combat damage to a creature, destroy that creature at end of combat."

Palliation Accord

Whenever a creature an opponent controls becomes tapped, put a palliation counter on Palliation Accord.
Remove a palliation counter from Palliation Accord: Prevent the next 1 damage that would be dealt to you this turn.

Thrive

Put a +1/+1 counter on each of X target creatures.

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.)

Novijen, Heart of Progress

{T}: Add {C}.
{G}{U}, {T}: Put a +1/+1 counter on each creature that entered this turn.

Betrayal

Enchant creature an opponent controls
Whenever enchanted creature becomes tapped, you draw a card.

Vigean Graftmage

Graft 2 (This creature enters with two +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{1}{U}: Untap target creature with a +1/+1 counter on it.

Helium Squirter

Graft 3 (This creature enters with three +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{1}: Target creature with a +1/+1 counter on it gains flying until end of turn.

Cytoplast Root-Kin

Graft 4 (This creature enters with four +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
When Cytoplast Root-Kin enters, put a +1/+1 counter on each other creature you control with a +1/+1 counter on it.
{2}: Move a +1/+1 counter from target creature you control onto Cytoplast Root-Kin.

Getting

Kros, Defense Contractor

At the beginning of your upkeep, put a shield counter on target creature an opponent controls.
Whenever you put one or more counters on a creature you don't control, tap that creature and goad it. It gains trample until your next turn. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

Bloom Hulk

When Bloom Hulk enters, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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.)

Contentious Plan

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Draw a card.

Aquastrand Spider

Graft 2 (This creature enters with two +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{G}: Target creature with a +1/+1 counter on it gains reach until end of turn. (It can block creatures with flying.)

Battlegrowth

Meadowboon

When Meadowboon leaves the battlefield, put a +1/+1 counter on each creature target player controls.
Evoke {3}{W} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

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.)

Keep Watch

Curse of Predation

Enchant player
Whenever a creature attacks enchanted player, put a +1/+1 counter on it.

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.)

Forced Adaptation

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

Fuel for the Cause

Counter target spell, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Borrowing 100,000 Arrows

Draw a card for each tapped creature target opponent controls.

Sporeback Troll

Graft 2 (This creature enters with two +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{1}{G}: Regenerate target creature with a +1/+1 counter on it.