T'Challa, the Black Panther (Borderless)

Whenever T'Challa enters or attacks, create a tapped Vibranium token. (It's an artifact with indestructible and "T: Add C. This mana can't be spent to cast a nonartifact spell.")`
Whenever you cast an artifact spell with mana value 4 or greater, put two +1/+1 counters on T'Challa.