Glitchless Proph-Only Frenzy Henchmen | Bonus with HM Despair of Dunes

For a specific person that will know with certainty they're being called out when reading this. See: It can be done with frenzy, henchmen and a Prophecies-only build without that much trouble; surely you can do it with access to the entire pool, PvE-only skills and heroes. It's not black magic. You don't have to be a "top level player" either.

Since the henchmen are incompetent at dealing damage I tweaked the standard bonus tactics, which would have been:
[0] Kill stuff up until and including the boss attacking our Ghostly Hero.
[1] bonus boss 1
[2] bonus boss 1 bonus spawn
[3] bonus boss 2
[4] bonus boss 2 bonus spawn
[5] bonus boss 3
[6] bonus boss 3 bonus spawn
[7] gg

The change: I keep the final two bonus bosses alive until ~40 seconds are left on the timer. Then I finish both of them. This way, the bonus boss bonus spawns don't have time to reach the Ghostly Hero and your main mission success isn't risked.
[0] Kill stuff up until and including the boss attacking our Ghostly Hero.
[1] bonus boss 1
[2] bonus boss 1 bonus spawn
[3] the friends of, but not bonus boss 2 themself
[4] the friends of, but not bonus boss 3 themself
[5] wait for the timer to hit 00:40
[6] bonus boss 2 and bonus boss 3
[7] gg

No, this is not too risky considering Alesia and Lina kept the team alive against the combined damage output of the two bosses just fine. You'll have heroes and it takes purpose to make heroes underperform Alesia.