Go Arcane Comet as a default rune page. You won't be needing Transcendence because we are going FULL DAMAGE!

Go Dark Harvest against squishy enemy teams. Run the same rune path every time.

You will start Doran's Ring 90% of the time. Only time you start Corrupting Potion is if you are against poke and want to survive. Even so I'd still start Doran's Ring most of the time.

MYTHIC ITEMS:
Only two Mythic Items you'll ever go is Luden's Tempest and Night Harvester. Go Luden's Tempest as a general item. And buy Night Harvester when against a lot of squishy enemies.

Full Builds:
These are the only build paths you only need to go.

Situational Items:
YOU WILL NEVER GET Morellonomicon, Banshee's Veil, etc. BECAUSE YOUR MAIN GOAL IS TO DO THE MOST DAMAGE POSSIBLE AND LET YOU TEAM CLEAN UP IF YOU DIE!
Buy Mejai's Soulstealer if you are super fed and can stack up the item.
Buy Horizon Focus if the enemy is long ranged.
Buy Lich Bane if the enemy builds no MR.
You can swap Zhonya's Hourglass for any of these items.