Ultron, Evolved AI

Ultron has flying as long as it has 4 or more counters on it.

Whenever you draw your second card each turn, put a +1/+1 counter on Ultron.

{3}, Remove a counter from a permanent you control: create a 1/1 Drone token (an artifact creature Invention with flying.) Activate only as a sorcery.

{2}, Sacrifice an artifact token: Draw a card.