Demon of Vex

As an additional cost to cast this spell, sacrifice
an artifact.
Demon of Vex gains Trample if it has
a +1/+1 counter on it.
"In the Cathedral of Gix they built a machine to
open the way to Vex. It worked, but broke. After
the carnage, one realized that any machine breaking
would summon, and that the ritual foundations laid
to control it were what was important."