The skeleton summoner definitely takes more damage than the spectre/zombie version. You’re regularly resummoning them, which means more standing still. And the skeletons don’t soak up as much area damage as the zombies do by simply being in the way of stuff, although that may not apply to you since I see you have both. Plus I see you’re not using a shield. Queen’s Decree or Femurs of the Saints have nice benefits, but you lose quite a bit of defense without the block/life/resists that a shield give you. I’m still using wand/shield on CharmingOssifier.
As for damage, I’m running into similar issues in tier 10+ maps. I can stay alive or I can clear incursions, but not both. It’s gotten to the point where I’ll do a few lower-level maps to build up temple connections, because I can pretty easily clear through incursions up to about tier 8. Then once I’ve got most of the rooms connected, I’ll do my higher level maps and just try to kill an architect in the last few incursions, which usually (though not always) can be done even if you don’t clear things insanely fast.