Video: https://www.youtube.com/watch?v=4HrPoRACxcM

This is a low stat TI solo build I came up with. The only dps character required is a countess with a calamity blade and a cupid. All my characters are using ult90 gear. My DPS countess in the video has extremely low stats, and you should be able to easily get a countess with higher stats than mine with a decent ult set with accessories.

Key Tips:

ASSAULT:

• Use Joust on all crystals if your Countess stats are as low like mine.

BUILD:

• Ensure your app stack is within the Hermit Golem radius for healing during combat.
   

Wave 16 (Upgrade Wave):

• Upgrade the app stack buff beam first, followed by the outside buff beam. After that, upgrade whatever you want.
• Be careful of Harbingers, especially when using an Adept.
   

Wave 17 (Boss Wave):

• It's ok if your outside minions or reflect beams die during the wave. Their role is to buy time. You can replace them after the wave.
• The flying mech sometimes takes forever to kill, but thats fine. The build can hold a long time.
• Allow the tavernkeep to pin you against the tavern wall. You are inside of a strength drain + healing aura and you should have a full ab1 up. You are invincible. The only way you can die here is if your ab1 goes down, or if he hits you into the water. But if you position yourself between him and the tavern, he can only knock you back into the building. Again, its ok if the tavernkeep kills your minions. You can replace them after the wave.

Wave 18 (Old One Wave):

• The build can hold a very long time, even with the minimum stats i posted. Take your time and play safe. If you are ever low hp, just back off and wait for the cupid to heal you up.
• Make sure you are blasting music loud enough so you can barely hear the game sounds, it helps you dodge :)

Feet:

• Wait for the stomp, then wait for the fireball cast. It's safe to Joust on his feet during the fireball cast. If you joust during a stomp, you might die if you are not positioned correctly.
• Make sure you have a full AB1 available for the chest. I like to cancel AB1 while killing the second foot.
   

Chest:

• The chest is the most dangerous spot, so always start with a full AB1.
• Green lasers are safest near the chest or at a significant distance.
• For blue lasers, strafe jumping makes them slow and easy to dodge.
• Make sure you dodge the arm shockwaves, they do a lot of damage.
• Try to stay in the middle of the platform, if you dodge too far to the left or right, its hard to dodge the arm slams.

Head:

• Standing right next to his head is the safest position to avoid being knocked off the platform.
• Joust at a slight angle for a longer duration and more damage.