msem-instigator

Flying, haste
Ride {1}{R} ({1}{R}: Transform this and attach it to target creature you control without a Mount. Ride only as a sorcery.)

Flying, haste
Whenever Scourge of the Skies attacks, you may have it deal 5 damage to target creature.

Breach (Whenever this deals combat damage to a player, you may have it become an Aura Curse until your next turn. Attach it to that player.)
At the beginning of your end step, discard a card. Then draw a card if an opponent is cursed.

Reveal the bottom four cards of your library. Choose up to one permanent card with mana value 3 or less from among them and put it onto the battlefield. Put the rest on the bottom of your library in any order.

Counter target permanent spell. (Then exile this card. You may cast the creature later from exile.)

{2}{R}: Target creature can't block this turn.

{U}: Sea Strider gets +1/-1 until end of turn.
{U}: Sea Strider gets -1/+1 until end of turn.

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
When Sea's Allure enters, gain control of target creature for as long Sea's Allure remains on the battlefield.

Trample
When Sealer of Pacts enters, sacrifice any number of permanents, then draw that many cards.

When Sear, Forged of Lava enters, create a 3/3 red Panda creature token, then attach it to that token.
Equipped creature gets +3/+3, has flying, haste, and “Whenever this creature dies, it deals 3 damage to target opponent or planeswalker.”
Equip {2}{R}{R}

Menace
Whenever Searing Sandwurm is dealt damage, it deals that much damage to target player or planeswalker.

Flying
Whenever Searshot Dragon deals combat damage to a player, it deals that much damage to target creature that player controls.
{1}{R}: Searshot Dragon gets +1/+0 until end of turn.

Seaside Skimmer can't be blocked if you've cast a Dragon spell or Adventure spell this turn.

Trample
Seasoned Adventurer enters with two +1/+1 counters if you control seven or more lands.

Search your library for up to four basic land cards with different names, reveal them, put them into your hand, then shuffle.

Choose one or more —
• Target player draws two cards.
• Counter target spell.

Take an extra turn after this one. During that extra turn, you may cast spells you own not named See the World from outside the game by tapping an untapped Scout you control in addition to paying their mana costs.
Exile See the World.

Breach (Whenever this deals combat damage to a player, you may have it become an Aura Curse until your next turn. Attach it to that player.)
Each cursed opponent must attack with at least one creature each combat if able.

At the beginning of your upkeep, you gain 1 life. Then if your life total is greater than or equal to your starting life total, you gain an additional 1 life and scry 1. Then if your life total is greater than or equal to three times your starting life total, you win the game.

Lifelink
When Seeker of Lost Secrets leaves the battlefield, you may pay 2 life. If you do, search your library for a card, put that card into your hand, then shuffle.

Return target permanent to its owner's hand. You may put a permanent card that shares a card type with it from your hand onto the battlefield.

Destroy target land. Add {R}{R}.

Another target player reveals their hand. You may choose an instant or sorcery card from it and cast it without paying its mana cost.
Fuse (You may cast one or both halves of this card from your hand.)

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever a +1/+1 counter is put on Sejiri Skyhunter, it gains flying until end of turn.

Reveal the top five cards of your library. Put one of those cards into your hand. Target opponent chooses two of those cards. Exile the chosen cards, then put the rest into your hand.