Replication Technique

Demonstrate (When you cast this spell, you may copy it. If you do, choose an opponent to also copy it. Players may choose new targets for their copies.)
Create a token that's a copy of target permanent you control.

Spellweaver Duo

Assist (Another player can pay up to {6} of this spell's cost.)
When this creature enters, you may return target tapped creature to its owner's hand.

Play of the Game

Assist (Another player can pay up to {6} of this spell's cost.)
Exile all nonland permanents.

Creative Technique

Demonstrate (When you cast this spell, you may copy it. If you do, choose an opponent to also copy it.)
Shuffle your library, then reveal cards from the top of it until you reveal a nonland card. Exile that card and put the rest on the bottom of your library in a random order. You may cast the exiled card without paying its mana cost.

Skystreamer

Assist (Another player can pay up to {4} of this spell's cost.)
Flying
When this creature enters, target player gains 4 life.

Excavation Technique

Demonstrate (When you cast this spell, you may copy it. If you do, choose an opponent to also copy it. Players may choose new targets for their copies.)
Destroy target nonland permanent. Its controller creates two Treasure tokens.

Game Plan

Assist (Another player can pay up to {5} of this spell's cost.)
Each player shuffles their hand and graveyard into their library, then draws seven cards. Exile Game Plan.

The Twelfth Doctor

The first spell you cast from anywhere other than your hand each turn has demonstrate. (When you cast that spell, you may copy it. If you do, choose an opponent to also copy it. A copy of a permanent spell becomes a token.)
Whenever you copy a spell, put a +1/+1 counter on The Twelfth Doctor.

Dwarven Lightsmith

Assist (Another player can pay up to {5} of this spell's cost.)
When this creature enters, creatures your team controls get +1/+1 until end of turn.

Magma Hellion

Assist (Another player can pay up to {6} of this spell's cost.)
Trample, haste

Silverquill Lecturer

Creature spells you cast have demonstrate. (Whenever you cast a creature spell, you may copy it. If you do, choose an opponent to also copy it. Each copy becomes a token.)

Bring Down

Assist (Another player can pay up to {3} of this spell's cost.)
Destroy target creature with power 4 or greater.

Lava-Field Overlord

Assist (Another player can pay up to {7} of this spell's cost.)
Flying
When this creature enters, it deals 4 damage to target creature an opponent controls.

Romana II

Vigilance
{1}, {T}: Create a tapped token that's a copy of target token that entered this turn.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Huddle Up

Assist (Another player can pay up to {2} of this spell's cost.)
Two target players each draw a card.

Out of Bounds

Assist (Another player can pay up to {3} of this spell's cost.)
Counter target spell.