Leidenfrost effect refers to the phenomenon that may occur when a droplet of liquid is released on a substrate which temperature is above the boiling temperature of the liquid. Indeed, beyond this temperature, the droplet may generate enough vapour to stabilise a thin film on which the droplet sits avoiding any contact with the substrate. This effect is sometimes wanted, sometimes is to be avoided, sometimes ignored according to the domain of application. In this talk, we first discuss the past and future of this effect before generalising the concept. Then, two `special’ substrates will be envisaged; they are nicknamed ‘special’ because they are not a flat solid. The first considered surface is smooth and reversibly deformable: a liquid. And the second one is rough and irreversibly deformable: a granular bed. While the liquid may look like the most ideal substrate ever, some limitations are revealed because of the thermal properties of the liquid and because of the motion inside the liquid. On the other hand, for the granular bed, the droplet manages to locally fluidise the granular material and, in some conditions that will be discussed, manages to dig in the granular bed. Deux salles, deux ambiances. Authors: Jun Zou, Wei Wang, Fangye Lin : Zhejiang University Hatim Machrafi, Pierre Dauby, Laurent Maquet, Benjamin Sobac, B. Darbois-Texier, A. Duchesne, M. Brandenbourger, A. Rednikov, P. Colinet : Université de Liège, ULB (at the moment of the work)