A creature “evolves” when one or more +1/+1 counters are put on it as a result of its evolve ability resolving.
September 25, 2014 · Khans of Tarkir
If a permanent has multiple instances of extort, each triggers separately.
July 13, 2013 · Magic 2014
If a permanent has multiple instances if extort, each triggers separately.
May 1, 2013 · Dragon’s Maze
A fused split spell has two sets of characteristics and one converted mana cost. The converted mana cost of the spell is a number equal to the total amount of mana in its two mana costs, regardless of color.