You Cannot Pass!

Destroy target creature that blocked or was blocked by a legendary creature this turn.

Eiganjo, Seat of the Empire

{T}: Add {W}.
Channel — {2}{W}, Discard Eiganjo, Seat of the Empire: It deals 4 damage to target attacking or blocking creature. This ability costs {1} less to activate for each legendary creature you control.

Yoshimaru, Ever Faithful

Whenever another legendary permanent enters the battlefield under your control, put a +1/+1 counter on Yoshimaru, Ever Faithful.
Partner (You can have two commanders if both have partner.)

Isamaru, Hound of Konda

Flowering of the White Tree

Legendary creatures you control get +2/+1 and have ward {1}.
Nonlegendary creatures you control get +1/+1.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Gideon, Battle-Forged

+2: Up to one target creature an opponent controls attacks Gideon, Battle-Forged during its controller's next turn if able.
+1: Until your next turn, target creature gains indestructible. Untap that creature.
0: Until end of turn, Gideon, Battle-Forged becomes a 4/4 Human Soldier creature with indestructible that's still a planeswalker. Prevent all damage that would be dealt to him this turn.

Kytheon, Hero of Akros

At end of combat, if Kytheon, Hero of Akros and at least two other creatures attacked this combat, exile Kytheon, then return him to the battlefield transformed under his owner's control.
{2}{W}: Kytheon gains indestructible until end of turn.

Kytheon, Hero of Akros // Gideon, Battle-Forged

Anafenza, Kin-Tree Spirit

Whenever another nontoken creature enters the battlefield under your control, bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Thalia, Guardian of Thraben

First strike
Noncreature spells cost {1} more to cast.

Thalia, Heretic Cathar

First strike
Creatures and nonbasic lands your opponents control enter the battlefield tapped.

Plains

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Mox Amber

{T}: Add one mana of any color among legendary creatures and planeswalkers you control.

Kataki, War's Wage

All artifacts have "At the beginning of your upkeep, sacrifice this artifact unless you pay {1}."