Modular

Modular is a keyword ability that allows artifact creatures to come into play with a number of +1/+1 counters, and put those counters on another artifact creature when the creature goes to a graveyard. Modular appeared in the Darksteel and Fifth Dawn sets.

From the ()

Reminder text

The latest reminder text for modular reads "This comes into play with N +1/+1 counters on it. When it's put into a graveyard, you may put its +1/+1 counters on target artifact creature."