Karlov gains two counters whenever you gain life, so you want to maximize the number of times you gain life, not how much life you gain.You can do this through cards that gain you life whenever common things happen, like Blood Artist, Drana's Emissary, and cards with extort
Magic: The Gathering is no stranger to crossovers with other properties
Spend some time considering all your options and how the cards best synergise to get the most out of the cards and have the best playing experience.
Final Fantasy was the first MTG set to combine both
Realms Uncharted is Gifts Ungiven for lands, and it fits beautifully into this deck
If the list is removed and reprints of these cards become available, however, more and more people would be interested in these formats