If this were the case then we might think that a “faction team” run could also be bugged (especially for Mirrored Halls), but it’s not – as long as your team for battle #1 is any combination of ABC and/or DE and you clear the delve as a whole, it counts as faction team.
Team strategy: Devour Spirit Fox to create Skulls (freeing Persistence to double skull damage vs. Green targets) then summon a new Spirit Fox into slot #1. Repeat if desired, otherwise cast Persistence for DPS and Spirit Fox for Mana Drain. (Yes, I realize I could have put Persistence first, but whatever)
Team prior to boss room battle (note the empty slot #1)
Well, the spec for faction team is that you started with a team of 4 faction troops (whatever happens thereafter doesn’t matter as long as you win the delve). The spec for no casualties is that you finish with the same 4 units (team code IDs) as you started with, even if resummoned. But in my case, the 4 finishing units aren’t even the same as the 4 starting ones.
This logical error is probably due to sloppy programming, because the programmer is too lazy to check properly for permutations, so he took the (incorrect) shortcut which I stated above.
Or… it could be a way to not punish a player for having his team shuffled. It’s much more frequent in the Labyrinth because that’s the gimmick of those troops, but there are also other delve rooms with shufflers – e.g., Dust Devil (in the oh-so-rare Tier I rooms) or Bulette.
That is a nice hypothesis, but wouldn’t it also imply that bringing a troop that can Transform itself (e.g. Doppelganger) would ruin a “no casualties” run if by the boss room you have a different Troop in your lineup than you started with?
Transformed Doppelganger during room 2 (into a Venoxia)
Result: was NOT acknowledged as “no casualties” run (+20 Renown for new record Delve level only)
Alternatively, if it was measured by empty slots wouldn’t that imply that if you started with an empty slot then it cannot possibly be considered “no casualties”?
Because, fortunately, this isn't the case.
Duergaroth Delve with only 3 Troops (1 empty slot): Cunning, Clockwork Sphinx, and Amethialas
Result: Successfully acknowledged as “no casualties” run (+30 Renown for new record Delve level + new no casualties)
So … yeah, we really do have a bug here with “no casualties” runs not being checked properly. Sometimes a run with casualties + summons will be credited as “no casualties” and sometimes a run with transforms (but no casualties) will NOT be credited for “no casualties”.
Please let me explain myself: the point of my top post was to mention that the game doesn’t check permutations properly. I was not addressing the issue that they define (specify) a “no casualty” run on criteria which does not agree with the common meaning of “no casualty” in the English language, and just went along with that specification (and pointed out that they didn’t even implement that correctly).
That said, now, here on this chord, I do agree that said specification is unnatural, and that tracking the actial death count would make more sense. After all, the current specification might merely be another product of the programmer’s ‘elaborate effort on sloppiness’ that plagues this game here and there: instead of using the natural specification, for whatever reason they implemented the current one which is logically (literally) incorrect (and they even managed to implement that incorrectly).
(Concerning the issue of no casualty run for a 3-unit team, I admit that I never tested that. I did test that for faction delve, and it didn’t score; I probably confused the two in my memory.)