Activate Rattleclaw Mystic's morph ability by paying {2}, turning it face-up.
Ratteclaw Mystic triggers twice, adding {G}{G}{U}{U}{R}{R}.
Activate Master of the Veil's morph ability by paying {2}{U}, turning it face-up.
Master of the Veil triggers twice, turning Rattleclaw Mystic and Master of the Veil face-down.
Repeat.

Infinite blue mana

Infinite green mana

Infinite red mana

Rattleclaw Mystic

Panoptic Projektor

Master of the Veil

Activate Ashnod's Altar by sacrificing Master of the Veil, adding {C}{C}.
When Master of the Veil dies, Yarus' second ability triggers, returning Master of the Veil from your graveyard to the battlefield face down, then turning it face up.
Master of the Veil triggers, turning itself face down.
Repeat.

Infinite colorless mana

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Yarus, Roar of the Old Gods

Ashnod's Altar

Combos with "Master of the Veil"