msem-instigator

Survivors you control have haste.

Target attacking creature gets +3/+1 and gains trample until end of turn. (Then exile this card. You may cast the creature later from exile.)

Enchant creature you control
When Nylea's Benefaction enters, scry 2.
Enchanted creature gets +3/+3 and has reach.

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] Target creature you control can't be blocked by creatures with power 2 or less this turn.
[Lore III] Draw a card.

Indestructible
As long as your devotion to green is less than five, Nylea isn't a creature.
Whenever another creature you control deals combat damage to a player, draw a card.
{1}{G}: Until end of turn, another target creature you control gains haste and can't be blocked by creatures with power 3 or less.

Enchant creature
Whenever you cast a green spell, enchanted creature gets +2/+2 until end of turn.

Deathtouch
When Nyx-Eater Basilisk enters, exile up to one target enchantment.
{2}{G}, Discard Nyx-Eater Basilisk: Exile target enchantment.

Trample
Whenever you attack with another creature with power 4 or greater, put a +1/+1 counter on OH-14 Diamond.

Menace
When OM-6 Walker dies, OM-6 Walker deals damage to each player equal to twice the number of nonbasic lands that player controls.

Trample
When Oakcudgel Giant enters, you may destroy target artifact or enchantment.

Equipped creature has “{T}: This creature deals 1 damage to any target.”
Equip {3}

Reach
When Oaken Sentry enters, you gain 1 life for each creature card in your graveyard.

Whenever a creature you control dies, Oakpoint gets +4/+0 until end of turn.

Search your library for two basic land cards, reveal them, put them into your hand, then shuffle.

Whenever you cast a cryptic spell, Oasis Cattle gets +1/+1 until end of turn, then untap it. (Artifacts, enchantments, and modal spells are cryptic.)

Trample
Assault {1}{G} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
Whenever a creature you control with a +1/+1 counter on it deals combat damage to a player, draw a card.

This spell costs {1} less to cast for each card you've drawn this turn.
You may reveal a land card from outside the game and put it into your hand. If it's basic or a Desert, put it into the battlefield instead.

Search your library for a basic land card or Desert card, reveal it, put it into your hand, then shuffle.
Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Oathbreaker Orc attacks each combat if able.
Whenever Oathbreaker Orc attacks, it deals 2 damage to defending player unless that player sacrifices a permanent.

{T}: Put a luster counter on Object of Awe.
{1}{R}, {T}: Discard up to X cards, then draw a card for each card discarded this way. X is the number of luster counters on Object of Awe.
{3}{R}: Until end of turn, Object of Awe becomes an X/X red Phoenix creature with flying, where X is the number of luster counters on Object of Awe.

Obliterating Blast deals 3 damage to any target. A creature dealt damage this way this turn can't be regenerated this turn. If that creature would die this turn, exile it instead.

Obscoriate deals 4 damage to target creature or planeswalker. The next time that permanent would die this turn, instead put a basalt counter on it, it becomes a Mountain land named Charred Remains, loses all other card types, and gains “At the beginning of your upkeep, Charred Remains deals 1 damage to you.” (It has “{T}: Add {R}” and loses abilities it already had.)

Observation Field enters with three charge counters on it.
{2}, {T}, Remove a charge counter from Observation Field: Draw a card and gain 2 life.
{T}, Sacrifice Observation Field: Shuffle any number of target cards from your graveyard into your library.

This spell costs {1} less to cast for each artifact and/or enchantment you control.
Trample
{1}, Sacrifice another cryptic permanent you control or exile a cryptic card from your graveyard: Put a +1/+1 counter on Observer of Aeons. (Artifacts, enchantments, and modal spells are cryptic.)

Whenever you attack, you may double target attacking creature's power. If you do, sacrifice it at the beginning of the next step.
Whenever one or more red creatures you control enter, creatures you control get +1/+0 and gain trample until end of turn.