Simic Signet

Overrun

Creatures you control get +3/+3 and gain trample until end of turn.

Telling Time

Look at the top three cards of your library. Put one of those cards into your hand, one on top of your library, and one on the bottom of your library.

Tetsuko Umezawa, Fugitive

Creatures you control with power or toughness 1 or less can't be blocked.

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Cloudform

When Cloudform enters, it becomes an Aura with enchant creature. Manifest the top card of your library and attach Cloudform to it. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)
Enchanted creature has flying and hexproof.

Frilled Mystic

Flash
When Frilled Mystic enters, you may counter target spell.

Mystic Snake

Flash
When Mystic Snake enters, counter target spell.

Staff of Nin

At the beginning of your upkeep, draw a card.
{T}: Staff of Nin deals 1 damage to any target.

Orochi Hatchery

Orochi Hatchery enters with X charge counters on it.
{5}, {T}: Create a 1/1 green Snake creature token for each charge counter on Orochi Hatchery.

Simic Guildgate

Simic Guildgate enters tapped.
{T}: Add {G} or {U}.

Quench

Counter target spell unless its controller pays {2}.

Simic Locket

{T}: Add {G} or {U}.
{G/U}{G/U}{G/U}{G/U}, {T}, Sacrifice Simic Locket: Draw two cards.

Kaseto, Orochi Archmage

{G}{U}: Target creature can't be blocked this turn. If that creature is a Snake, it gets +2/+2 until end of turn.

Overwhelming Stampede

Until end of turn, creatures you control gain trample and get +X/+X, where X is the greatest power among creatures you control.