Threader

{t}: Thread. (Attach this creature to another target
creature with X time counters on it equal to the target
creature's converted mana cost. At the beginning of
each upkeep, remove a time counter. When the last is
removed, gain control of the attached creature and it
becomes an Arathim in addition to its other types.)
Being attached to one for more than a day made
the attachment permanent, with forceful removal
resulting in the deaths of both parasite and host.