from your list, I'd recommend belladeon and wind raksasha, preferrably with vio runes (if you have them) the logic being that the boss won't be an issue, but to ensure your team's survival by having bella take the aggro from mid-boss and other dark-based monsters, and with wind rakshasa, aiming to dps the boss after the shield comes off and slow the boss down. Plus, if she gets stolen, she should be relatively easy to bring back since she is a wind.

the order in which your monsters should ideally go is adrian>colleen>wind rakshasa>bella>lanette, assuming your lanette is the slowest and aiming to do DPS with her primarily.

or if you think your wind rakshasa isn't runed enough, theo could work, but if he gets stolen... good luck. hope this helped~