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 ()

Rulings

• If an Arcbound creature gets enough -1/-1 counters to make its toughness 0 or cause the damage on it to now be lethal, the Modular ability will still give another artifact creature a number of +1/+1 counters equal to the number the Arcbound creature had before it got -1/-1 counters.
• For the comes-into-play ability, the number of counters the permanent gets is equal to the number that follows "modular" on the card.
• For the leaves-play ability, the number of counters on the permanent at the time it left play is what's relevant; the number after "modular" doesn't matter.
• When a creature with modular leaves play, you may put the counters onto a single target artifact creature. You can't split them among two or more artifact creatures.

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."