Your search for "siege behemoth 144" revealed the following:
Siege Behemoth (CMA) from Commander Anthology, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: Jason A. Engle Card Text:HexproofAs long as Siege Behemoth is attacking, for each creature you control, you may have that creature assign its combat...
Siege Behemoth (C14) from Commander 2014, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: Jason A. Engle Card Text:HexproofAs long as Siege Behemoth is attacking, for each creature you control, you may have that creature assign its combat...