Thanks for your answers !
I'll try the plugin in a first time, but in fact I don't like to use external plugins for Construct 2. Maybe it's silly to think that but I prefer focus myself on C2 possibilities.
TELLES0808 > Thank you for your reply :)
It's a bit complicate to use matrix, in a first time but it's very intersting. I'll try to implements "avoiding solid" to my monsters in a first time.
By the way, what do you mean by "top mask" ? an invisible sprite bigger than the monster, pinned to it to manage collision / overlapping with other solids ?