Heres what I know about the bug.
31% chance for four Kerberos to summon zero wargs when each ally dies. There is a 69% chance for them to summon at least one.
There is a 75% chance for Kerberos to summon nothing when an ally dies (including itself). With four Kerberos, you have a 0.75 ^ 4 chance.
The current glitch has certain passive traits carry over when an on-death (or on-damage) summon immediately overwrites another dying troop. The underlying dying troop is not properly cleaned up. Gate Guardian then is able to trigger off Wargs summoned over dead Kerberos. Said Wargs can also trigger their own “pack master” trait.
When they start getting Wargs out, their traits can also trigger when you kill them for a chance at even more Wargs. More than one can be summoned from a single death trigger on a single death. If you happen to kill all four Kerberos and glitch them, replacing them with four Wargs while still having the Kerberos traits active, there will be an 87% chance to summon at least one Warg whenever one dies.
The same Warg can, by the way, trigger both Gate Guardian and Pack Master when it dies. Even having it down to a single Warg and Kerberos, killing the Warg can result in the entire team being repopulated by Wargs. I’ve also seen the final Warg summon another Warg via Pack Master, who then triggered Gate Guardian because the slot was glitched (I suppose Gate Guardian is checked after self death-summon traits, so your Infernal King doesnt get blocked by a Warg).
Usually, you’ll be able to eventually wear them down over time, even if you glitch all four slots. Just make sure to bring a team that can heal and deny browns and purples. It only takes one Kerberos cast to make the battle pretty much unwinnable, since you’ll often have to hew through about 15-20 wargs before you win, which is very difficult if you are down a troop.