I'm back cause I saw your update hahah ;-)

I see you are trying to force more lifegain triggers, I would play any other card with extort wich is not the Pontiff.... The pontiff is way to costly to put down and you basically play him for his extort trigger, the fact that he gives it to everything seems really good but often you don't have the mana to pay up...

If you look for more lifegain triggers and about the same CMC go for Patron of the Kitsune it's a 5/6 flyer (thats already better than the pontiff + it triggers on EACH attack trigger, wich will probably trigger more than the Sunscorch Regent :-)

Slap in a Eight-and-a-Half-Tails and you can cast him on instant speed if needed + the Eight Tales is completely underrate, protecting ALL your permanents for only 3 mana and the ability to make Karlov unblockable...

And now that we are on the subject of unblockable/protection, Mother of Runes and the new Giver of Runes are an absolute auto include in your deck. Eight-tales and Mother did soooo much work and basically protected karlov on instant speed from spot removal and on the offense make him unblockable if they play the right color combo. Now that you als get the Giver of Runes it's even better. Trust me on this one, it will make your life so much easier! Nothing sucks more than when your fat Karlov get's nuked down, and turn 1 mother of runes, turn 2 karlov is most of the time GG for at least 1 player at the table.

Another absolute powerhouse in my deck was Ajani, Caller of the Pride at only 3 mana he often hit my board around turn 3/4 where Karlov was already 6/6, it's really not that hard if you have a turn one Soul Warden and then suddenly Karlov is a 6/6 flying doublestrike in turn 3, needless to say you often removed 1 opponent around turn 4-5 :)

As usual really hope this tips will help you a bit more!