Vampyre II

Vampyre II is demon/anti-IC program is an extremely powerful variant on the Demon series of compiler programs, credited to the notorious Waycon Kidd. Very expensive and rare, Vampyre dismantles any Target program it attacks, adding the "victim's" abilities to itself. The only type of programs Vampyre cannot absorb are other Demons and programs involving virtual realities (such as Psychodrome).

When Vampyre attacks a program, it rewrites the program into itself as one-time code, so that every program "eaten" by a Vampyre (up to a total of 6) can then be used by that Vampyre once, and then it is erased. This constant re-writing of code lines and activation of subroutines does put a strain on the program's logic systems, however: every time you activate one of the absorbed programs you must roll a D10 greater than the current number of programs stored. Failure means that the Vampyre has "crashed," purging all its stored programs, and rendering it useless until the 'runner leaves the net, removes the Vampyre from his deck, and reinstalls it.

Source

 * Chromebook Volume 1, pg.92