msem-instigator

Whenever Shifty Fink attacks, if you have more cards in hand than defending player, it gets +2/+1 until end of turn.

When Shifty Squirrel enters the battlefield, you gain 3 life.
Sacrifice a creature: Transform Shifty Squirrel.

When you unveil Shining Elementalist, creatures can't block this turn.

Flying, lifelink
Whenever Shioki, Imperial Heir attacks, exile any number of other target nonland permanents you control, then return those cards to the battlefield under their owner's control.

Equipped creature gets +2/+2 and has flying and lifelink.
When equipped creature deals combat damage to a player, unattach Shionoshio, Ocean's Vow, then transform it.
Equip {W}{U}
Shionoshio can be your commander.

Whenever Shoreline Stormers deals damage to a player, draw a card.
{2}{U}: Target creature can't be blocked this turn.

Search your library for two basic land cards, reveal them, put them into your hand, then shuffle. (Then exile this card. You may cast the creature later from exile.)

Vigilance
Whenever Sibling of All Elements attacks, it gains flying until end of turn if you control a creature with flying. The same is true for first strike, double strike, deathtouch, indestructible, lifelink, menace, and trample.

Prevent all combat damage that would be dealt to Silent Reaver.
Prevent all combat damage Silent Reaver would deal to creatures.

{T}: Untap another target nonland permanent. Activate only as a sorcery.

{2}{U}, {T}: Look at the top card of your library. If it's a Scout card or a card with an Adventure, you may reveal it and draw a card.

When Silver Gardener enters the battlefield, create a 1/1 green Saproling creature token.
Unveil {2}{G}{W} ({2}{G}{W}: Transform this. Unveil only as a sorcery.)

Whenever Sir Roger Wimbledon deals combat damage to a player, you may put an exiled creature card you own into your hand.

Whenever a creature dealt damage by Slave Child this turn dies, you may pay {B}. If you do, transform Slave Child.

Ward {2}
Slippery Bunyip can't be blocked except by creatures with Adventures.

{T}: Target opponent loses 2 life. Activate only if you gained life this turn.

(Transform this if it's not attached to a creature. Pay {2}{W} as a sorcery to unattach it.)
Enchant creature you control
Slopestrider's Chariot's rider gets +1/+1 and has double strike.

Whenever a creature enters the battlefield without counters during your next turn, you may put two +1/+1 counters on it.

{2}, Remove a +1/+1 counter from a creature you control: Draw a card.

Destroy target creature with flying. (Then exile this card. You may cast the creature later from exile.)

Target opponent discards two cards. You gain 2 life. (Then exile this card. You may cast the creature later from exile.)

Lifelink
When you attain Sojourner of the Beyond, create two 1/1 white Spirit creature tokens with flying. They gain haste until end of turn.

Put a +1/+1 counter on each creature you control. (Then exile this card. You may cast the creature later from exile.)

Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)
When Sower of Wishes enters the battlefield, reveal the top three cards of your library. Put all land cards revealed this way into your hand and the rest back on top in any order.

Spearhead deals X damage to target player. (Then exile this card. You may cast the creature later from exile.)