First (Choose 1)Start with "Restorative Shot" to sustain in lane. "Restorative Shot" can be replaced with "Healing Rite" or "Extra Regen" as well.

Early Game Items"Rebuttal" is perfect for the close range combat and meleeing with Billy. "Melee Lifesteal" has some great synergy with 'Blasted', make sure to melee after 'Rising Ram' as well. Finish off with "Backstabber" for some early damage and great utility.

Mid Game Items"Escalating Resilience" and "Spirit Resilience" will be Billy's best forms of defence. "Greater Expansion" has some great synergy with all of Billy's spells, especially 'Chain Gang!'

Late Game Items"Juggernaut" will be first to get some slow resistance and extra health. Then get "Phantom Strike" in order to focus out important targets, especially mobile heroes like Mina and Vindicta. Lastly, obtain "Spellbreaker" and "Colossus" for even more defenses!

Situational ItemsPurchase items that are needed for the situation you're currently in. There are a bunch of good items to run on Billy.