Don't worry about time, it is quite critical that you make the
right decisions here.
I won't tell you what to do but Yulya can't cast more than one regular spell per turn though there are bonus action spells, though 5e says if you cast a spell as a bonus action, the other spell must be a cantrip, I don't care about such restrictions only that she has only one action per turn.
After researching it, I've decided that Yulya must edit her post.
As far as strategy, it's clearly a conflict of interest to help you but it looks like the odds of your success in this situation have dropped significantly even in 10 rounds, and since I loath Alice to complain about mistakes made in this encounter and supposed fairness, I will offer this reminder since Yulya, among others, are so tediuosly forgetful.
Yulya isn't the only immortal currently in your party capable of resurrecting automatically upon death at this time, and I don't mean the Diva in a mining outfit.
I'm not saying what will happen if you do, I don't even know, only that
she will revive upon death as foretold, and at least temporarily, have boosted abilities, though at a cost yet undecided.
I've said too much,
sigh I spoil you all so.
And if you think a firebomb will do anything more than destroy your chances at clearing the mine, and dooming the town, then think again. It's very low damage and easily avoided, but devastating to a wood lined mine.

Good luck!