I have a friend that is doing a one-shot. They are having us be level 20 and we are going to be fighting a celestial.

My idea was:

Bloodhunter V for Hexblade Pact and extra Attack as well as weapon and shield proficiencies.

Artificer III to use my intelligence as my hit and gain the steel defender

Wizard XII for bladesinger to increase martial capabilities and available spells drastically.

I will be using the Hedge race for its AC as well.

Is this a viable character? I have never played near to level 20 (highest has been level 8). If not, do you have any recommendations on what to change or do differently?

Edit: Thank you for the tips. I will make it Wizard 17/Artificer 3. Should my first level be in Wizard or Artificer?