Thundertrap Trainer

Offspring {4} (You may pay an additional {4} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
When this creature enters, look at the top four cards of your library. You may reveal a noncreature, nonland card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Mindspring Merfolk

Exhaust — {X}{U}{U}, {T}: Draw X cards. Put a +1/+1 counter on each Merfolk creature you control. (Activate each exhaust ability only once.)

Research Thief

Flash
Flying
Whenever an artifact creature you control deals combat damage to a player, draw a card.

Cloudkin Seer

Flying
When this creature enters, draw a card.

Transit Mage

When this creature enters, you may search your library for an artifact card with mana value 4 or 5, reveal it, put it into your hand, then shuffle.

Micromancer

When this creature enters, you may search your library for an instant or sorcery card with mana value 1, reveal it, put it into your hand, then shuffle.

Deekah, Fractal Theorist

Magecraft — Whenever you cast or copy an instant or sorcery spell, create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it, where X is that spell's mana value.
{3}{U}: Target creature token can't be blocked this turn.

Prophet of the Scarab

Vigilance
When this creature enters, draw cards equal to the number of Zombies you control or the number of Zombie cards in your graveyard, whichever is greater.

Mischievous Mystic

Flying
Whenever you draw your second card each turn, create a 1/1 blue Faerie creature token with flying.

Naban, Dean of Iteration

If a Wizard you control entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Deranged Assistant

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Arcanis the Omnipotent

{T}: Draw three cards.
{2}{U}{U}: Return Arcanis to its owner's hand.

Serum Visionary

When this creature enters, draw a card, then scry 2.

Azami, Lady of Scrolls

Tap an untapped Wizard you control: Draw a card.

Clinquant Skymage

Flying
Whenever you draw a card, put a +1/+1 counter on this creature.

Gandalf, Friend of the Shire

Flash
You may cast sorcery spells as though they had flash.
Whenever the Ring tempts you, if you chose a creature other than Gandalf as your Ring-bearer, draw a card.

Triskaidekaphile

You have no maximum hand size.
At the beginning of your upkeep, if you have exactly thirteen cards in your hand, you win the game.
{3}{U}: Draw a card.

Elementalist Adept

Flash (You may cast this spell any time you could cast an instant.)
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Harbinger of the Tides

You may cast this card as though it had flash if you pay {2} more to cast it. (You may cast it any time you could cast an instant.)
When this creature enters, you may return target tapped creature an opponent controls to its owner's hand.

Gale, Waterdeep Prodigy

Whenever you cast an instant or sorcery spell from your hand, you may cast up to one target card of the other type from your graveyard. If a spell cast from your graveyard this way would be put into your graveyard, exile it instead.
Choose a Background (You can have a Background as a second commander.)

Laboratory Maniac

If you would draw a card while your library has no cards in it, you win the game instead.

Cynette, Jelly Drover

When Cynette enters or dies, create a 1/1 blue Jellyfish creature token with flying.
Creatures you control with flying get +1/+1.

Shipwreck Dowser

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When this creature enters, return target instant or sorcery card from your graveyard to your hand.

Triton Wavebreaker

Bestow {1}{U} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached.)
As long as this permanent is a creature, it has prowess. (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Enchanted creature gets +1/+1 and has prowess.