Dark energy

The TE reserve is refreshed on the first day of each week. TE from the previous week (if any remains) does not carry over. In patch 1.5, 250 TE is always given, 20 for each Bone Pillar and some amount based on the hero's level (I suggest you download the manual, everything is detailed there). Another 150 can be obtained from a grail structure, but that is rare.

I downloaded the manual, it's a very useful thing, but I didn't find the TE calculation principle there. Where can I learn in more detail how TE is credited to a hero with each level and if it's possible to raise only skeletons if such a skill exists? How can I check the amount of TE before a battle to know whether it's worth fighting this week or waiting for the TE replenishment at the beginning of the week?
Thanks in advance.