msem-instigator

Flying
Whenever you cast an instant or sorcery spell, Scourge of the Sun gets +1/+0 until end of turn. If you spent four or more mana to cast that spell, Scourge of the Sun gets an additional +1/+0 until end of turn.

Flying
Dragon spells and Adventure spells you cast cost {1} less to cast.

Flying
Whenever an artifact you control enters, you may activate one of its activated abilities without paying its cost.

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.

Flash
Menagerie — When Seven Seas Scourge enters, if there are five or more creature types among creatures you control, counter target spell with mana value 4 or less.

Flying
When Sha Long enters, each player chooses an artifact they control, then sacrifices the rest. If they don't control an artifact, they may return an artifact card from their graveyard to the battlefield. Repeat this process for creatures, enchantments, and planeswalkers.

Flying, haste
Whenever Shimmering Dragon attacks, for each creature you control, create a tapped and attacking token that's a copy of that creature. Exile the tokens at the beginning of the end step.

Flying
Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast your second spell each turn, draw a card.

Advance {3}{R}{R} (Cast this for {3}{R}{R} to advance it as it enters. {3}{R}{R}: Advance this as a sorcery.)
Flying, haste
Whenever Skiviar Scraplord advances, put a +1/+1 counter on it.