League idea from player - Echoes of Old War

A disclaimer: my English are not so good and this post is yet another league mechanic from the Player....

Some league idea:
Echoes of Old War

This league is based on the Karui theme.
After we killed the Beast, Karui came back, as Tukohama do. But not only one of the Karui Gods has arrived.
On the Wraeclast, Oriath and all over the World, old Karui Clans returned to bring the War. All lands get burned. The War Song is everywhere. The War is here!

So as mentioned before - all other Gods of the Karui arrived:
-Tasalio, Father of Water - Cold
-Ramako, Father of Light - Fire
-Valako, Father of the Storm - Lightning
-Tawhoa, Father of the Forest - Physical
-Hinekora, my Mother of Death - Chaos
-Arohongui, Daughter of the Moon - All other combined

At the locations we find the packs of the Karui monsters, that defend their totems with some of offering to their God. When we kill all pack we can claim those. But some packs contain the War Chief of this Clan, that holds the War Banner of the Clan that gives strong buffs to the all monsters nearby. When we kill the War Chief we collect his War Banner.

In this league we will meet some NPC (as always) that talk to us after certain kills of the Warchiefs and says that he finds a city of the Karui. Karui has returned to the old place, where they sity was standing, and rebuild it. And now it's the main place of all it's clans. (Main league mechanic)

The karui sity consists of the parts:
-Armory
-Weaponry
-Treasury
And some other Main nodes.
Also, it has a lot of small nodes, like Houses, small Armories and other.

Every part of the city controlled by one of the Karui Clans. When we gain a War Banner we can donate it to the God of some Clan in one of the Main City Nodes. (e.g. we donate War Banner of the Ramako's Clan to the Arohongui God) p.s. we can't donate same banner to the same God. When we are donating banner to the God, it will increase the power of this Clan in this part of the City.
Combinations of the City part and the clan that controls it give different final rewards. e.g. if Armory is controlled by Ramako's Clan, we will get the items with powerful Fire stat on it.

After we donate some amount of the banners to the Gods. A clan that holds the most power will create (or call) the Avatar of its God. e.g. Avatar of the Arohongui, Daughter of the Moon.
When the Avatar is arrived, we can't donate the banners, we should kill the Avatar before we can do it again.
When the Avatar arrived, we will be able to get in the Karui City and clear all its parts to collect rewards. (As mentioned before - reward will be different for each Clan that controls that part of the City). All Main parts of the City have its own mini-Boss, that also will be the same as Clan that controls that zone. At the end - we will kill the Avatar of the God, and it will end the event.

After we kill Avatar the power of its Clan will reset and its zones will be reclaimed by other Clans. This Clan will arrive in another part of the City.

One zone can be influenced by multiple Clans, but only by one of them controlled. It depends on the power of this Clan in this zone (not work for the small zones, that can be influenced only by one Clan).

The interface that I can see to represent the influence of the clans - we have a Partial 3D map of the City(like in Skyrim global map), the zones of it will be painted in the color of the Clan that controls it.

To be clear - this is really basic idea, but I really want to hear your opinion on it.