beast of burden has power and toughness each equal to the total number of creatures in play.
(note: a portion of urza's legacy prerelease beasts of burden were printed without the foil datestamp and expansion symbol. in the regular version (not this variation) these details show up in the right half of the type line.)
“If it is meant to be nothing but a machine,” Karn finally asked Jhoira, “why did Urza build it to be like me?”