Starscream, Seeker Leader

Living metal (During your turn, this Vehicle is also a creature.)
Flying, menace, haste
Whenever Starscream deals combat damage to a player, if there is no monarch, that player becomes the monarch.
Whenever you become the monarch, convert Starscream.

Starscream, Power Hungry

More Than Meets the Eye {2}{B} (You may cast this card converted for {2}{B}.)
Flying
Whenever you draw a card, if you're the monarch, target opponent loses 2 life.
Whenever one or more creatures deal combat damage to you, convert Starscream.

Starscream, Power Hungry // Starscream, Seeker Leader

Throne of the High City

{T}: Add {C}.
{4}, {T}, Sacrifice Throne of the High City: You become the monarch.

Custodi Lich

When Custodi Lich enters, you become the monarch.
Whenever you become the monarch, target player sacrifices a creature.

Marchesa's Decree

When Marchesa's Decree enters, you become the monarch.
Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life.

Staunch Throneguard

Vigilance
When Staunch Throneguard enters, you become the monarch.

Court of Locthwain

When Court of Locthwain enters, you become the monarch.
At the beginning of your upkeep, exile the top card of target opponent's library. You may play that card for as long as it remains exiled, and mana of any type can be spent to cast it. If you're the monarch, until end of turn, you may cast a spell from among cards exiled with Court of Locthwain without paying its mana cost.

Peer into the Abyss

Target player draws cards equal to half the number of cards in their library and loses half their life. Round up each time.

Court of Ambition

When Court of Ambition enters, you become the monarch.
At the beginning of your upkeep, each opponent loses 3 life unless they discard a card. If you're the monarch, instead each opponent loses 6 life unless they discard two cards.

Swamp

Thorn of the Black Rose

Deathtouch
When Thorn of the Black Rose enters, you become the monarch.

Crown of Gondor

Equipped creature gets +1/+1 for each creature you control.
When a legendary creature you control enters, if there is no monarch, you become the monarch.
Equip {4}. This ability costs {3} less to activate if you're the monarch.

Revenge of Ravens

Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life and you gain 1 life.

Feast of Succession

All creatures get -4/-4 until end of turn. You become the monarch.

Garrulous Sycophant

At the beginning of your end step, if you're the monarch, each opponent loses 1 life and you gain 1 life.