(Disclaimer, this is not the only way to do this, it is just how I did it, don't yell at me I am fragile)

The Artifact of Command to chose your items.

As many Infusions as your gosh damn pockets can carry until your health reaches >2000 (unless you are able to pick up a Rejuvenation Rack then you just need >1000)


().

Eventually a Lepton Daisy when you are ready.

Alternately a Foreign Fruit equipment item.


And any items you need to survive while you get the kills to increase your health.

Start the game as REX.

Getting items along the way and choose accordingly:

• Common items: Whatever you want to take to stay alive.
  
• Uncommon: Infusion until you have >2000 health. Then get Lepton Daisy.
  
• Legendary: Rejuvenation rack.

Then all you need to do is get healed by the teleporter event for half you hp and boom. Done.