Sword of the Instant Change

Sword of the Instant Change enters the battlefield
with counters equal to the instant rate of change of
2x^2 -8 (plugging in the amount of mana you cast
it for for x after its simplified).
Equip {1}
Equipped creature gets +X/+X and gains trample, vigilance, and haste.
"That sword is pointless, what harm could it do?"
-Last words of Jacob