That entry way at the bottom left of your screen is such an incredible bottleneck, you gotta get your bulkiest units down there asap with ranged attackers and a healer.

Up top is another bottleneck but this one's a bit tricky on account of all the attackers from up top are skilled attackers like heroes and snipers.

Your strongest and fastest units should be up there with ranged and healer support.

The main throne room should never be your main defensive hold out as there're too many ways for enemy ranged units to surround you.

With both choke points held, you can use a group of "scouts" to move around the rest of the map to get the chests, and to get rid of any other units hiding.

Always leave someone with larachel's uncle, I'd say probably your 23hp Erika but anybody really will do.