is there any way to avoid trapdoor ? i completed 95% of the map to end to fall in a trapdoor... i remember with my rogue i had the option to go down by pressing Z but now with samurai i automaticly fall through it .. it is samurai only or it will happen with every other classes ?

Rogues/Monks/Ninja have the passive ability of detecting trapdoors and allowing you the choice to go down or not.

TDs are noticeably harder but also house better drops for those brave enough to venture into the depths

kk and it is capped at 1 trapdoor per maze or i can fall through it more than once?

Its random The higher the level you are when you start a new maze the bigger it becomes though so with increased size comes increased chance for one or more to spawn. My personal record was 13 of them before the monsters were so overpowered that I didnt feel like being in it any more.