there is still no conclusion to the seal in silvertear lake. below Midgardsormr. this is the first thing that came to mind when yoshi said to look back at HW.
though no clue where that would lead us unless we are pulling a massive connection to FFIV here.
Underworld, Land of the Summons, Tower of Babil, the Moon.

Afterall there must be a reason we didn't fight golbez or any other FFIV bosses (like the fiends) so far. especially during the Omega raid where it was expected