The boss gate that requires killing a minotaur to open - the rats just jump into minotaur's mouth, suffocating it.
Core room, with Chloe using a magic sword making a fire wall around the core - Kehma made a tiny flying glass golem from the empty bottles of mana potions, that golem touched the core while Chloe's attention was on dealing with the rats.
On the opposite side:
Haku's army reach a 'quiz room' that is not actually made with DP, just made to look like one (the door isn't magically locked, a brute force can blow through it but Haku didn't know)
Kehma used a simple trick question where he knew the smart Haku would overthink the answer and get it wrong.
Eventually by the time Haku's group manage to open it (thanks to the 'idiot' among them), there's a "Under Construction" sign behind it.
The actual dungeon core of his side was never down below, it's actually hidden among the initial pitfall traps that Haku made sure to avoid after realizing they exist.