Yea. I'm just peeved that you went down in the vampire fight without using a flare, and you probably did right in saving them for later given the nature of this dungeon. Think nothing of it.
Bit of a counterpoint - I haven't read most of the bestiary entries, but typically in previous editions, the first or primary attack is typically the worst - be it because they have a higher attack, higher damage, or a rider effect (grab/trip/save/etc. if hit) than subsequent attacks, or are required to land before using even worse attacks (say, a giant kraken first needing to grab you before swallowing you whole).
One of the things in general for x/day things is you never want to end up doing that thing you do in RPGs - saving items for "emergencies" then end up with 99 of them and only needing 2.
Personally, I look at it this way - If I have a thing I can do X times per day, that will only do one thing, recovering it long rest, while at the same time having 2 lvl 3 spell slots that's much more flexible with how I use them, also recovering them at the long rest. I'd worry about not using the latter effectively enough than the latter.
Not saying "You're doing it wrong!" or your thinking is critically flawed - my time with characters casting spells in 5e has been rather limited compared to other editions.
I don't remember the fight exactly but I think his non use of it was fine. It didn't work out this time but I assumed he was waiting in case one of them grappled him to use it then to avoid the bite.
Another related note. I've noticed with abilities that require you to announce ahead of time are sometimes difficult to use when playing online or streaming because of usually having to interrupt someone before they roll. @DansGaming @AdamKoebel Is there a way to "roll" these abilities in roll20 so instead of having to interrupt all they have to do is hit the button to "roll" it and if they get it in before the attack roll is made it works and if they don't it doesn't expend a use and better luck next time.
Right now once the mimic room melted the question is, DID THE LOOT MELT?, there must have been some loot right? right? please?
There was no loot lol