msem-instigator

Vigilance
Whenever a legendary creature you control enters, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

When Sylvan Explorer enters, reveal the top card of your library. If it's a land card, put it onto the battlefield tapped.

Enchant creature
When Sylvan Majesty enters, search your library for a Forest card, put it onto the battlefield tapped, then shuffle.
Enchanted creature gets +3/+3.

Search your library for a land card, reveal it, put it into your hand, then shuffle.

Target creature gets +2/+2 until end of turn. Draw a card if that creature has a counter on it.

Reach
Whenever another creature enters, untap Sylvan Subversive.

Scry 2, then reveal the top card of your library. If it's a basic land card, put it onto the battlefield tapped. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.)

When Symbiotic Sprout dies, create two 1/1 green Saproling creature tokens.

(As this Discovery enters and after your draw step, add a progress counter. Stop after you've discovered.)
Archive 6 (As this enters, shuffle the top six cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Draw a card from each of your libraries.
discover — When you draw the last card from the archived library, create a 4/4 blue Sphinx Wizard creature token with flying.

Whenever you cast a blue spell, each opponent mills a card.

Synchronous Battle Armor and equipped creature get +1/+1 for each artifact you control.
Whenever equipped creature attacks, tap up to three target creatures.
Reconfigure {3}{U}{U} ({3}{U}{U}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Flying
Synchronous Hellkite enters with a +1/+1 counter for each other artifact you control.
Sacrifice three artifacts: Return Synchronous Hellkite from your graveyard to the battlefield.

Counter target spell unless its controller pays {X}. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

When Syncretic Master enters, look at the top X cards of your library, where X is the number of basic land types among lands you control. Put one them into your hand and the rest into your graveyard.

Menace, prowess

Wu Xing (Add effects based on the number of colors of mana spent to cast this spell.)
1 | Put a +1/+1 counter on each creature you control.
3 | Those creatures gain vigilance and deathtouch until end of turn.

Syndicate Sycophant can't block.
When a creature scavenges Syndicate Sycophant, you may search your library for a card named Syndicate Sycophant, reveal it, put it into your hand, then shuffle.
Scavenge {2}{B} ({2}{B}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

Enchant creature
When Synergistic Curiosity enters, create a 2/2 blue Rogue creature token.
Enchanted creature gets +1/+1 and can't be blocked by creatures with flying.

Whenever a creature you control becomes blocked, you may return it to its owner's hand.
The first spell you cast during your postcombat main phase each turn costs {W}{U} less to cast. This effect reduces only the amount of colored mana you pay. (For example, if you cast a spell with mana cost {1}{U}, it costs {1} to cast.)

Flying
When Syrina's Brood enters, look at the top six cards of your library, then put them back in any order.

Flying
When Syrina, the Dragon Queen enters, gain control of target nonland permanent for as long as you control Syrina, the Dragon Queen.
{2}{U}: Exile Syrina, the Dragon Queen. Return her to the battlefield at the beginning of the next end step.

Enchant creature
Enchanted creature has deathtouch and “{1}{B}: Regenerate this creature.”

Look at target player's hand. Draw two cards, then discard a card.

Enchant creature
When Sythian Scripture enters, put two +1/+1 counters on enchanted creature.
Enchanted creature gets +1/+1 and has indestructible and lifelink if you controlled a white legendary creature or planeswalker as you cast Sythian Scripture.