Skeletons promoting is a buff to all skelly related pieces, lich, tombstone and necro. And nerco is already a strong piece. Its strange also that such backtracking-able minion gets promotion, upgrades were previously reserved mosty for minions who could not retreat.
Idk, just loose idea, maybe increase all skelly cost by 1 except +++, but then make them upgrade into higher tiers when killing stuff.

Some poeple talked about possibility to make your own units transparent with new nullmage, and that made me think if its possible to change taurus same way, so he could rush his own units for emergency transport. Deadly if used wrong. Might be tricky when combined with hostages, so they might need to recieve rushimmunity, or rush abbility should be changed into ranged. But then antimage would be buffed this way.