On Last Wish, first Riven encounter (before the heart encounter), it groups ALL rez's in one spot in one part of the map. This means that unless you happen to flawless the encounter or know it really well (my team doesn't) it's impossible to beat, cause it means there aren't enough people left in the other room. Also, if you die on the second/higher level or the top, your rez is STILL on the bottom in that spot. Which means nobody can be revived after you progress one level...