Ah, I tried to activate Bombard that way, but it wasn't clear that it had actually bombarded, so I never really tried it again. If this weren't a 7DRL, this is where I would be chiding you on not providing more visual feedback, but it's understandable given time constraints.
The pre-Aura boss fights were good. I'm glad you took Witch down to 3 HP, since the difficulty in that fight is entirely in approaching her. After I got Aura, literally every potentially difficult encounter was dealt with by running in a circle. Of course, this didn't work on the queen, although if Erupt does what it looks like it does, then I could have gotten away with it there, too.
If you were planning any updates to the game, I'd recommend more Aura-resilient enemies. Some examples:
- A 1 HP enemy that can move when you move on the firetail. This breaks a fundamental rule of the game, so I can understand how you might be reluctant to add something like this.
- An enemy that is invincible to conventional attacks that can only be defeated by being surrounded by X fire tiles -- perhaps 3?
- An enemy that actively seeks out your fire tiles to extinguish them. Aura would still deal with this guy like anything else if you have your tiles already set up, though.
- An enemy that retreats 1 tile on taking damage.
You say that Aura is more powerful on level 6. I would contend that it is no more powerful on level 6, and in fact is most powerful on level 3. Consider the following layout:
.1 2
3 4 5
.6 7
If I have tiles 1, 2, 3, and 4 lit up, I can kill every enemy adjacent to any of those hexes by running in a circle on those tiles, regardless of health. I can then move to tile 5 or 6 and repeat the process, chaining Aura indefinitely as I snake through the stage in diamond formations. Taking Aura sixth not only delays how early you can get it going (only on the last level!), but it also makes it harder to start up. Since Aura 3 deals effectively infinite damage to everything except the Queen, there's no benefit in making it more powerful.
Another more global change that you could make is to make enemies more willing to step on the firetail. This makes it harder to create an Aura loop, although it probably makes it easier to execute the other attacks.