If you have your vw out in the start, just sic it on the pally until you need the bubble. Don't do it in the beginning of the match because that's a waste. Just start running away and instant DoTing him up. Once you get all your spells on (use CoA, not CoTongues), fear him and put immolate on. Tap twice for mana and then drain life. If he gets to close (within 10 yards), just fear. Once he uses the bubble, he will either heal or try to get closer to you. Just do whatever to get back to full health/mana, and if you haven't used your vw keep it out, but if you bubbled get out felhunter. Once they finish they should be close to full health, so just repeat the process. Kiting paladins isn't hard at all, their highest range spell (or weapon for that matter) is 10 yards, and all warlock spells are 20-36 yards. If he becomes immune to fear, just keep running until you get some distance and leave combat. That will reset diminishing returns. If he is immune and close to you... good luck and hope you can fake him out (start running away and then randomly switch directions). Also, if damage isn't critical, use drain mana instead of drain life. Paladins are useless without mana, so every bit you drain is worth it.