Kukulkan on Rage

I won't eat yellow snow, but thanks for the reminder.

Not sure what mode this is for, but I think the purchase orders aren't very optimal.

You don't get ANY penetration until the last item, and it honestly should be built much sooner than that. You also get Soul Reaver as the 3rd item, and I just think it's too expensive for what it brings at that stage of a match/build.

I think Bancroft's Talon is a solid lifesteal item for any mage, but in Kukulkan's case, I think he might be better served with Polynomicon (for basic attack follow-up to Zephyr) or Pythagorem's Piece (for teamfight function and CDR, which he'd appreciate). I'd probably build Rod of Tahuti only after I had some pen.

So, a more optimal standard build for him would probably be something like Shoes of Focus (or Magi as preferred), Warlock's Sash (if you want that over Thoth for the health/survivability), Spear of the Magus, Polynomicon, Rod of Tahuti, Situational (could be Obsidian Shard for more pen against tankier teams, or Soul Reaver in this position if preferred, or Gem of Isolation, or any number of other items.