Have seen a few teams for Mayan dungeon event achievement (Magus or Sentinel), but had little luck with them. This one works for me on auto:
Bass Eddie - Alchemy/Cosmic
Awakened Magus Wicker Owl Evolved (5 Purple stars) - Singularity
Awakened Magus Lord of Light (4 Purple stars) - Celestial/Cosmic
Magus Hierophant - Primordials
Best time I saw was 2m10s. Average around 2m45s. Think the longest was about 3m40s, and that was only once. Never got close to dying.
Only tip: At the start, target any toon that doesn't have Invulnerability. As soon as Shaman loses his Invulnerability, or if all toons have Invulnerability, target him instead. This way you can hopefully start applying negative effects (which usually require the hit to land to activate) right from the start.