This is my ember surv build I'd like to share. I've done this with solo with my tower jester starting from the lowest possible wave, since there's no harbingers on that first wave. Play time for a full run was around the 3h mark. The outward gas traps are to get easy mana for upgrading and jestering the towers with presents. I sell them when I'm satisfied with the towers I got and replace them with the outward darkness traps. If I feel like it I sometimes try to get 2 du darkness and gas traps as well leaving even more room to play with.
I'm not sure what stats are minimum to play this build,
Aurastack (13 du) + gas trap (3 du) + buffbeam (5 du) + 2x 1du reflect (2 du) = 23 du total
The minions I use on the buff at hint 1 are: 2 mages, 2 spiders, 5 archers
Aurastack (13 du) + gas trap (3 du) + buffbeam (5 du) + 3x 1du reflect (3 du) + 2x 5du walls (10 du) = 34 du
The minions I use on the buff at hint 2 are: 3 mages, 2 spiders, 11 archers (No ogres from this side, so stack them in the middle of the buff as much as possible so ogres at the walls cannot reach them.
Tower battery at hint 3:
buffbeam (5du), 6x 1du reflect (6 du) = 11 du
120 - 23(north) - 34(south) - buff/reflect(11) = 52 du to play with jestering.
I usually settle for 10 towers with up to 2 harpoons and the rest lightnings. (40 du) and 4 darkness traps (12 du)
You could obviously use more towers, try some ethereals or proxies for instance instead of the darkness traps. Variations are always fun to try.
Hint 4: Move the wall and reflect a little over the edge or ogres may walk past it to the tower battery.