Invigorating Hot Spring

Invigorating Hot Spring enters with four +1/+1 counters on it.
Modified creatures you control have haste. (Equipment, Auras you control, and counters are modifications.)
Remove a +1/+1 counter from Invigorating Hot Spring: Put a +1/+1 counter on target creature you control. Activate only as a sorcery and only once each turn.

Upriser Renegade

Upriser Renegade gets +2/+0 for each other modified creature you control. (Equipment, Auras you control, and counters are modifications.)

Rugged Highlands

Rugged Highlands enters tapped.
When Rugged Highlands enters, you gain 1 life.
{T}: Add {R} or {G}.

Towashi Guide-Bot

When Towashi Guide-Bot 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.)

Seshiro's Living Legacy

Tales of Master Seshiro

(As this Saga enters and after your draw step, add a lore counter.)
I, II — Put a +1/+1 counter on target creature or Vehicle you control. It gains vigilance until end of turn.
III — Exile this Saga, then return it to the battlefield transformed under your control.

Tales of Master Seshiro // Seshiro's Living Legacy

Forest

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.)

Roaring Earth

Landfall — Whenever a land you control enters, put a +1/+1 counter on target creature or Vehicle you control.
Channel — {X}{G}{G}, Discard Roaring Earth: Put X +1/+1 counters on target land you control. It becomes a 0/0 green Spirit creature with haste. It's still a land.

Goro-Goro, Disciple of Ryusei

{R}: Creatures you control gain haste until end of turn.
{3}{R}{R}: Create a 5/5 red Dragon Spirit creature token with flying. Activate only if you control an attacking modified creature. (Equipment, Auras you control, and counters are modifications.)

Kami's Flare

Kami's Flare deals 3 damage to target creature or planeswalker. Kami's Flare also deals 2 damage to that permanent's controller if you control a modified creature. (Equipment, Auras you control, and counters are modifications.)

Coiling Stalker

Ninjutsu {1}{G} ({1}{G}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Coiling Stalker deals combat damage to a player, put a +1/+1 counter on target creature you control that doesn't have a +1/+1 counter on it.

Thundering Raiju

Haste
Whenever Thundering Raiju attacks, put a +1/+1 counter on target creature you control. Then Thundering Raiju deals X damage to each opponent, where X is the number of modified creatures you control other than Thundering Raiju. (Equipment, Auras you control, and counters are modifications.)

Flame Discharge

Flame Discharge deals X damage to target creature or planeswalker. If you controlled a modified creature as you cast this spell, it deals X plus 2 damage instead. (Equipment, Auras you control, and counters are modifications.)

Uncharted Haven

Uncharted Haven enters tapped. As it enters, choose a color.
{T}: Add one mana of the chosen color.

Rabbit Battery

Haste
Equipped creature gets +1/+1 and has haste.
Reconfigure {R} ({R}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

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.

Akki Ember-Keeper

Whenever a nontoken modified creature you control dies, create a 1/1 colorless Spirit creature token. (Equipment, Auras you control, and counters are modifications.)

Mountain

Ogre-Head Helm

Equipped creature gets +2/+2.
Whenever Ogre-Head Helm or equipped creature deals combat damage to a player, you may sacrifice it. If you do, discard your hand, then draw three cards.
Reconfigure {3} ({3}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Jukai Preserver

When Jukai Preserver enters, put a +1/+1 counter on target creature you control.
Channel — {2}{G}, Discard Jukai Preserver: Put a +1/+1 counter on each of up to two target creatures you control.