• What version are you using?
  70200.41
• Can the issue be reproduced, and if so, how?
  Kill Kin'garoth, second boss of the third wing (Hoffnungsbruch in deDE)
• If there was an error message, please include it.
  Found an unknown spell (250604) please report it

Unconfirmed data from the WH Database:

http://ptr.wowhead.com/spell=250541/7-3-raid-antorus-bonus-roll-loot-boss-01
Garothi Worldbreaker

http://ptr.wowhead.com/spell=250574/7-3-raid-antorus-bonus-roll-loot-boss-02
Felhounds of Sargeras

http://ptr.wowhead.com/spell=250575/7-3-raid-antorus-bonus-roll-loot-boss-03
Antoran High Command

http://ptr.wowhead.com/spell=250576/7-3-raid-antorus-bonus-roll-loot-boss-04
Portal Keeper Hasabel

http://ptr.wowhead.com/spell=250577/7-3-raid-antorus-bonus-roll-loot-boss-05
Eonar the Life-Binder

http://ptr.wowhead.com/spell=250578/7-3-raid-antorus-bonus-roll-loot-boss-06
Imonar the Soulhunter

http://ptr.wowhead.com/spell=250580/7-3-raid-antorus-bonus-roll-loot-boss-08
Varimathras

http://ptr.wowhead.com/spell=250581/7-3-raid-antorus-bonus-roll-loot-boss-09
The Coven of Shivarra

http://ptr.wowhead.com/spell=250582/7-3-raid-antorus-bonus-roll-loot-boss-10
Aggramar

http://ptr.wowhead.com/spell=250583/7-3-raid-antorus-bonus-roll-loot-boss-11
Argus the Unmaker

Not sure how to get the other numbers in the triplets

I've been doing some reworking so I don't have to manually collect IDs any more, the version that will be out for 7.3 won't require a database update.
Thanks though!