Predecessor Builds > Argus > Two Bedrooms No Rugs
The Plan
Your first tier 2 item is always "Alchemical Rod" when you hit 700 (or 750) gold. You should back as soon as you have the money for it, and then immediately start building "Orb of Growth".
After that's built, you may wish to finish "Azure Core" if you've gotten at least 300 stacks on "Alchemical Rod", otherwise start building into "World Breaker" by builiding "Void Crystal" before finishing "Azure Core".
The last two items are fills, but I see success with "Caustica" because it gives mana regen and some decent magical power bonuses. I like having a little more mana sustain so I sometimes build "Timewarp" as a last item for that little bit more mana regen for more right-click sustainability.
Azure Core - Gives a spike of magical power mid-game
Orb of Growth - Provides a little healing and some extra nice bonuses once fully built
World Breaker - Void Crystal adds % magical power with every hit of the right click ability, meaning you get full advantage of all stacks from World Breaker once built.
Caustica - Magical pen, but more built for it's passive and mana regen.
Timewarp - Built for extra regen and better cooldowns
Playstyle
The playstyle of this build means the first two major items need to be built by minion kills before you can fully come online, so play extra cautiously starting out.