Whenever a permanent you control enters, you may put a living counter on it.
Permanents with living counters on them are 2/2 artifact creatures in addition to their other types.

Trample
Whenever Skittertiller deals combat damage to a player, put a +1/+1 counter on it.

Whenever you cast a green spell, choose up to X, where X is the number of green mana symbols in that spell's mana cost —
• Create a 1/1 white Human creature token.
• Put a +1/+1 counter on a creature you control.
• Put a trample counter, vigilance counter, or a reach counter on a creature you control.
• Untap target land.

Trample
Whenever another creature you control becomes the target of a spell you control, create a token that's a copy of that creature, except it has haste. Sacrifice that token at the beginning of the next end step.

As an additional cost to cast this spell, sacrifice a creature.
When Skophos Conqueror enters, draw a card. Skophos Conqueror deals 2 damage to each opponent.

Trample
Whenever Skophos Raid-Veteran deals combat damage to a player or planeswalker or becomes the target of a spell you control, create a tapped Treasure token.

Menace
Whenever your Champion attacks, you may discard a card. If you do, draw a card.

When Skophos Warden enters, you may exile target artifact or enchantment an opponent controls until Skophos Warden leaves the battlefield.

Whenever Skotha enters or attacks, each opponent discards a card. Then you may return a permanent card with mana value 3 or less from your graveyard to the battlefield.
{B}{B}{G}{G}: Return Skotha from your graveyard to the battlefield, then put it on the bottom of its owner's library. Activate only as a sorcery.

{T}: Add {C}.
{3}, {T}: Create a 1/1 white Golem creature token. Spend mana of three different colors to activate this ability.
{T}: Put a +1/+1 counter on target creature. It gains flying until end of turn. Activate only as a sorcery and only if you control ten or more permanents.

When you cast this spell, copy it if you control a creature with flying. You may choose new targets for the copy.
Tap up to one target artifact or creature. Create a 1/1 blue Bird creature token with flying.

Flying
When Skylance Escort enters, put a vigilance counter on each creature you control.

Choose one —
• Skysnipe deals 5 damage to target creature with flying.
• Put a +1/+1 counter and a reach counter on target creature. Untap it.

Whenever you cast an instant or sorcery spell, Skyward Magus gets +1/+1 and gains flying until end of turn.

Reach
When this creature enters, create a green Subroutine enchantment token named MOUNT with “Whenever this Subroutine runs, target creature you control gets +2/+2 until end of turn.”

When this creature dies, it deals 3 damage to any target.
Cycling {B/R}

Sleeper Insurgent doesn't untap during your untap step.
Whenever Sleeper Insurgent becomes the target of a spell or ability you control, untap it. This ability triggers only once each turn.

Flash
Flying
When Sleeper Strix enters, tap up to one target creature.
You may look at an additional card each time you surveil.

Flying
Favored
Whenever another legendary nontoken creature you control dies, you may exile it. If you do, create a token that's a copy of it, except it has no name, it isn't legendary, and it is a Zombie.

Lifelink
Whenever this creature or another creature you control enters, if it entered from a graveyard or was cast from a graveyard, put two exalted counters on it.

When Slumbering Grove enters, search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Spellcharge 8

Enchant land you control
Enchanted land is a 6/6 green Serpent creature with hexproof and haste. It's still a land.
When enchanted land dies, return that card to its owner's hand.

Once each turn, when Smart Shopper enters or you cast a creature spell, you may create a Berry token. If three or more types of mana were spent to cast it, create two of those tokens instead.

When Smiling Sludge enters, create a Berry token.
Whenever you sacrifice a nonland permanent, target opponent loses 1 life and you gain 1 life.

Level up {2}{B}
[level 1-2] Deathtouch
[level 3+] Deathtouch