Caliv, Lord of Untruth

Whenever a creature you control has its base toughness changed, you gain 2 life.
{2}{g/u}{g/u}: Choose a creature type and color. Target creature or artifact becomes a creature of the
chosen type and color with your choice of flying, trample, or vigilance along with its other abilities
and has base power and toughness of your choice
of 1/1, 5/2, or 4/4 until end of turn.