As the title states, every on-hit explosion attack does not deal damage to the Hidden King shrines. This does not occur when hitting the Archmother shrines.
The following are the affected characters and abilities:
1) Rem, Pillow Toss
2) Kelvin, Frost Grenade
3) Warden, Alchemical Flask...
When throwing Conjure Dragon at most stairs, there is about a chance that the dragon will end up going backwards or even clipping into the floor. I find that it happens more often at the stairs near the spawns, and less commonly on the small set of stairs in the middle of the blue lane.