I’ve been grinding stage 8 on Invasion for a while now. It’s kinda wierd how you can’t know when you will get extra sigils, unlike in Raid/Bounty which you will know if you able to kill Valravan or not. All I can do is wish for extra sigils at the end of successful battle, without taking some extra action to earn it.
I know that Valraven can’t appear in Invasion stage 8 and replace random towers to decrease towers count each battle from 4 to 3. So I have an idea to make a 7th spacial Valravan tower.
Bell Tower (20 Red/Yellow)
Stats: attack-20, life-30, armor-40, magic-20
Spell: Blaring Defence - Silence one random enemy, all other allies gain [magic/2] armor.
Traits: Air Link / Invulnerable / Fleeing Dweller (Spawn a Valraven when destroyed)