If you are fast, you can use all the DU first wave and switch to upper. If you are struggling for time, build everything else and save the buff beams for next wave. Or build during the wave with your warden. But ideally you would like to be using upper first wave. Place minions between waves. Add more spiders and mages if needed.
During the boss phase i recommend placing your DPS near Hint 1. After the snowman is dead move to Hint 2. After that, move to Hint 3 and hopefully most hero bosses have been tower killed. Just finish them off.
23 December 2025
This got it done for me, thanks Edge! But man the timer is short, so you gotta run fast to get the build up.