How do I calculate the difference in cost of the two minions?
Start with the cost of the Evil minion in your hand, then subtract the cost of the Mortal at the Pond. Remember that costs cannot be negative, so if the result is below zero, treat it as zero instead.
Can I transform a Mortal I do not control into Evil from my hand?
Yes, though since it is a transform effect, control of the transformed minion will not change. The player who controlled the Mortal will control the Evil that came from your hand.
Can my opponent use this effect as well?
Yes!
Market
$0.45
Low
$0.24
Median
$0.50
