According to the many resources available this puzzle is very simple to solve, this is how it should be performed:
Phasing Portal onto enemy Lord Jaraxxus
Hero Power, Life Tap
Demonic Research to use life instead of mana to summon Lord Jaraxxus.
However after using Demonic Research and attempting to play Lord Jaraxxus it says “I Don’t have enough” and won’t let me continue. The Mana icon on Jaraxxus does not change.
I have 10 health, and Jaraxxus is 9 mana.