How to break through the Gate of Oblivion on Jebus in week 2?

mrshch
Your phrase isn't quite clear: "The first move is for the caster to buff the skeletons (to block the archers)."?

Dragons provide the first move against most neutral creatures, which allows you, for example, to speed up the skeletons and/or block the archers with dragons.

Added 13 minutes later

mrshch

Using skeletons as endless cannon fodder, not being stingy with them, since they recover quickly, and eventually grow in numbers. This is the preferred option.
If there is Raise Dead in the guild, then it's even better.

If you have Raise Dead, it's better to use larger units. Health points are restored, and it's much harder to take away 200 health from a dragon than from skeletons.
You need 2 magic power to raise a knight, 3 for a skeleton, and 4 for a wraith. This is without the Earth skill.

Added 6 minutes later

The first time, I used speed on the skeletons, and the cyclops took them out in the first turn, but all the other troops survived. And the skeletons recovered after a couple of battles.

Have you tried using demons?
Send me the save file from a couple of days before the battle, and I'll try to beat it.