Hello Citizens of Dalaran.
We have just released Koralon the Flame Watcher inside the Vault of Archavon.
Only those who already have The Secrets of Ulduar will be able to encounter him, if there is any player in the raid group without this achievement, the boss will not be available.
Regarding the Trial of the Champion requirement, we have agreed to downgrade it to the Keepers of Ulduar (10 or 25), instead of the Secrets of Ulduar.
Thank you very much and enjoy it.