Ancestral Vault

Ancestral Vault is a system that allows you to unlock new character entirely for free (and also obtain their dupes). All you have to do is finish 3 simple missions every day to obtain Mead of Rebirth and after you obtain 10000 of it, you can exchange it for one of the available characters (but currently there's just one).
Keep in mind that you can't obtain those characters in any other way - they're not available on any banner or in shards.
How long does it take to unlock one character?
You can obtain 240-300 Mead of Rebirth every day, depending on the missions you will receive. This means you will need 33-41 days to 'exchange' that for one character.
Still, keep in mind that roughly once per month you can obtain up to5000 - 12 000 Mead of Rebirth from Clan Hunt - the amount changes based on how well your Clan does in this boss killing mode.
How to access Ancestral Vault?
You can do it via your Clan screen!
Do I lose Mead or progress when I change guild?
You don't! So don't worry about changing guilds to find a better one.
Ancestral Vault Characters
Here's a list of currently available characters in this mode.