Arcbound Wanderer

Oracle Text

Modular—Sunburst (This enters the battlefield with a +1/+1 counter on it for each color of mana spent to cast it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Card Rulings

12/1/2004 This card has modular—sunburst, a combination of two keyword abilities. The sunburst ability sets the number for the modular ability. Basically, the number of +1/+1 counters the Wanderer gets as it enters the battlefield is equal to the number of colors of mana used to pay its cost.
12/1/2004 For the leaves-the-battlefield ability, the number of counters on Arcbound Wanderer at the time it left the battlefield is what’s relevant; the number of colors of mana used to pay its cost doesn’t matter anymore.
12/1/2004 When the Wanderer leaves the battlefield, you may put the counters onto a single target artifact creature. You can’t split them among two or more artifact creatures.
9/25/2006 If this creature gets enough -1/-1 counters put on it to cause its toughness to be 0 or less (or the damage marked on it to be lethal), modular will put a number of +1/+1 counters on the target artifact creature equal to the number of +1/+1 counters on this creature before it left the battlefield.