So uh... Here's something fun I'm trying.
Zyra Jungle. Chilling Smite, Magus. Use plants and autoattack-canceling the dragon to level 5 solo dragon. Get liandrys 2nd item. Do a lot of damage.
The trick is to make the dragon turn around by walking closer than your plant is to the dragon, then move away before it hits you.
Repeat this and the dragon never hits you and barely ever hits your plants.
Plants soak up two hits of dragon.