OVERVIEW
Carry is Be'lakor's most natural role, though he can also flex mid or offlane. For his skill build he wants to max Clone Image first, then Maisma. The cases where you want to max Pendulum first is when you're stomping the enemy hard and don't need the defensive power of Miasma or case when teamfights just aren't happening early. All of his talents are strong and deciding which he wants to pick is mostly up to personal preference and the game state. A good default talent build would be taking both Miasma talents, and then the clone and BAT talent.
As a universal hero he wants to get all stats at the start of the game. A casual cornucopia (pretend perseverance is a cornucopia) can later be upgrade into linkens if the game calls for it or it can just be sold. Manta Style is Be'lakor's most core item, he can Clone Swap with ANY illusions including manta illusions. With all those illusions Diffusal and Disperser (can't add Disperser on this website) become mighty good. Then it's stats. Stats, stats, stats. Be'lakor is a universal hero with illusions so nothing can boost his damage so effectively. Of course try and get stat items that actually work well with illusions like Skadi, Heart, and Butterfly. Get his aghs sooner rather than later as the utility is just out of this world. Same goes for his shard as it's his primary mobility tool.
For situation items Linkens in his best defensive item that also has some nice sustain and a good build up. Radiance for if the game is going really really really good. Armlet could be a super strong early game buy, but Be'lakor doesn't naturally purchase the sustain for it nor does it help with his mana problems so it's risky. A blink dagger for if there is a key target that needs to die. Abyssal, hex, or gleipnir could fill in for the CC Be'lakor lacks, hex is probably the best choice here.