Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Nikara, Lair Scavenger

Partner with Yannik, Scavenging Sentinel (When this creature enters the battlefield, target player may put Yannik into their hand from their library, then shuffle.)
Menace
Whenever another creature you control leaves the battlefield, if it had one or more counters on it, you draw a card and you lose 1 life.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Arcane Signet

Yannik, Scavenging Sentinel

Partner with Nikara, Lair Scavenger
Vigilance
When Yannik, Scavenging Sentinel enters the battlefield, exile another creature you control until Yannik leaves the battlefield. When you do, distribute X +1/+1 counters among any number of target creatures, where X is the exiled creature's power.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Sandsteppe Citadel

Sandsteppe Citadel enters the battlefield tapped.
{T}: Add {W}, {B}, or {G}.