Starting items:

Dark Seal + Refillable Potion is the most cost efficient start.
You can also start with Doran's Ring + 2 Health Potion.


If you have mana problems in lane get a Doran's Ring if you started Dark Seal

Next items:

Hextech Revolver and Aether Wisp gives you a huge powerspike early game, and enough movement speed with Celerity rune.

Core:

Hextech Revolver + Luden's Tempest + Sorcerer's Shoes

Finish Sorcerer's Shoes after Luden's Tempest
With these items you will delete their carries.

Average game:

Stomp:

Build:

After your core, you want to get
- Rabadon's Deathcap
- Void Staff
- Zhonya's Hourglass
Order can be changed depending on the situation.

Late game:

You will have to sell Hextech Revolver for a situational item:

Abyssal Mask: More tankiness with Health and Magic resist + enough damage with the passive
Banshee's Veil: Damage, Magic resist, and a spell shield
Liandry's Torment: Tankiness and flat magic pen
Lich Bane: More single target burst
+ others

Secondary Resolve with:

Mirror Shell/ Iron Skin and Second Wind

if you think you will get harassed a lot or it is a hard matchup in general.

If you are more experienced you can start Pale Cascade and hardshove the lane, but watch out for jungler ganks.

You can get Moonfall at level 3/4 or even later, its personal preference.