Heyo! I found inspiration from Jungroan's Frozen Legion "not a league starter". Hopefully FL will prove to be a strong bosser that's good at content like Heist, Legion, and Expedition.

https://www.youtube.com/watch?v=TtK02H2UrPk

https://pastebin.com/Hnc75E0H

Just getting into the build, Glacial Cascade compliments FL while providing knockback. Ice Golem helps meet crit/hit requirements. The Inquis ascendancy provides plenty of crit chance and defenses while setting enemy resistance to 0%. Chill/freeze should be powerful in The Forbidden Sanctum. Ancestral Warchief is high damage and creates a distraction. Heatshiver is a huge source of damage, as is Marohi Erqi. Mana might be an issue.

Cast speed and CDR help a lot. FL has a shotgunning effect with stacking AOE, making 3 statues have full coverage and 6 statues a high amount of overlap. It should take 2s to accrue 3 statues and 4s to accrue 6 statues. There's also the secondary delay of waiting for the statues to attack. Quite slow, but the gaps can be filled by glacial cascade, earthquake, wave of conviction, or absolution.

Anyway, it's just a theory -- everything's changing. Good luck & have fun!