Will Kenrith

+2: Until your next turn, up to two target creatures each have base power and toughness 0/3 and lose all abilities.
−2: Target player draws two cards. Until your next turn, instant, sorcery, and planeswalker spells that player casts cost {2} less to cast.
−8: Target player gets an emblem with "Whenever you cast an instant or sorcery spell, copy it. You may choose new targets for the copy."
Partner with Rowan Kenrith
Will Kenrith can be your commander.

Swamp

Magosi, the Waterveil

Magosi, the Waterveil enters tapped.
{T}: Add {U}.
{U}, {T}: Put an eon counter on Magosi, the Waterveil. Skip your next turn.
{T}, Remove an eon counter from Magosi, the Waterveil and return it to its owner's hand: Take an extra turn after this one.

Chronatog Totem

{T}: Add {U}.
{1}{U}: Chronatog Totem becomes a 1/2 blue Atog artifact creature until end of turn.
{0}: Chronatog Totem gets +3/+3 until end of turn. You skip your next turn. Activate only once each turn and only if Chronatog Totem is a creature.

Pact of the Titan

Create a 4/4 red Giant creature token.
At the beginning of your next upkeep, pay {4}{R}. If you don't, you lose the game.

Forest

Intervention Pact

The next time a source of your choice would deal damage to you this turn, prevent that damage. You gain life equal to the damage prevented this way.
At the beginning of your next upkeep, pay {1}{W}{W}. If you don't, you lose the game.

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Pact of Negation

Counter target spell.
At the beginning of your next upkeep, pay {3}{U}{U}. If you don't, you lose the game.

Quicksilver Fountain

At the beginning of each player's upkeep, that player puts a flood counter on target non-Island land they control of their choice. That land is an Island for as long as it has a flood counter on it.
At the beginning of each end step, if all lands on the battlefield are Islands, remove all flood counters from them.

Delaying Shield

If damage would be dealt to you, put that many delay counters on Delaying Shield instead.
At the beginning of your upkeep, remove all delay counters from Delaying Shield. For each delay counter removed this way, you lose 1 life unless you pay {1}{W}.

Chronatog

{0}: Chronatog gets +3/+3 until end of turn. You skip your next turn. Activate only once each turn.

Teferi's Protection

Until your next turn, your life total can't change and you gain protection from everything. All permanents you control phase out. (While they're phased out, they're treated as though they don't exist. They phase in before you untap during your untap step.)
Exile Teferi's Protection.

Leyline of Anticipation

If Leyline of Anticipation is in your opening hand, you may begin the game with it on the battlefield.
You may cast spells as though they had flash.

Eater of Days

Flying, trample
When Eater of Days enters, you skip your next two turns.

Glacial Chasm

Cumulative upkeep—Pay 2 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When Glacial Chasm enters, sacrifice a land.
Creatures you control can't attack.
Prevent all damage that would be dealt to you.

Krosan Grip

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Destroy target artifact or enchantment.

Chronomantic Escape

Until your next turn, creatures can't attack you. Exile Chronomantic Escape with three time counters on it.
Suspend 3—{2}{W} (Rather than cast this card from your hand, you may pay {2}{W} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Lethal Vapors

Whenever a creature enters, destroy it.
{0}: Destroy Lethal Vapors. You skip your next turn. Any player may activate this ability.

Kenrith, the Returned King

{R}: All creatures gain trample and haste until end of turn.
{1}{G}: Put a +1/+1 counter on target creature.
{2}{W}: Target player gains 5 life.
{3}{U}: Target player draws a card.
{4}{B}: Put target creature card from a graveyard onto the battlefield under its owner's control.

Chronosavant

{1}{W}: Return Chronosavant from your graveyard to the battlefield tapped. You skip your next turn.

Eon Frolicker

Flying
When Eon Frolicker enters, if you cast it, target opponent takes an extra turn after this one. Until your next turn, you and planeswalkers you control gain protection from that player. (You and planeswalkers you control can't be targeted, dealt damage, or enchanted by anything controlled by that player.)

Meditate

Draw four cards. You skip your next turn.

Awakening

At the beginning of each upkeep, untap all creatures and lands.

Sudden Substitution

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Exchange control of target noncreature spell and target creature. Then the spell's controller may choose new targets for it.

Vedalken Orrery

You may cast spells as though they had flash.

Mountain

Alchemist's Refuge

{T}: Add {C}.
{G}{U}, {T}: You may cast spells this turn as though they had flash.

Emergence Zone

{T}: Add {C}.
{1}, {T}, Sacrifice Emergence Zone: You may cast spells this turn as though they had flash.

Island

Slaughter Pact

Destroy target nonblack creature.
At the beginning of your next upkeep, pay {2}{B}. If you don't, you lose the game.

Tangle Wire

Fading 4 (This artifact enters with four fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
At the beginning of each player's upkeep, that player taps an untapped artifact, creature, or land they control for each fade counter on Tangle Wire.

Plains

Crop Rotation

As an additional cost to cast this spell, sacrifice a land.
Search your library for a land card, put that card onto the battlefield, then shuffle.

Summoner's Pact

Search your library for a green creature card, reveal it, put it into your hand, then shuffle.
At the beginning of your next upkeep, pay {2}{G}{G}. If you don't, you lose the game.