Skizzium, Makeshift Mechanic

Whenever an artifact creature you control is
dealt damage, create a Scrap artifact token.
Sacrifice X Scrap tokens: Put a Vehicle with converted mana cost X from your hand or
graveyard into play. Activate this ability only
once each turn.
{t}, {b}{b}: Put a -1/-1 counter on target artifact creature. Create a Scrap artifact token.