.-. I did 1 on 1 vs my Guildmate who used a similar build to this a while back. i degened him to death with fire and poison, interrupted the form/echo/self heal.
... there are many other ways, like What Now wisely said.
chillblains cost 25e and signet of disenchantment cost you all energy, is that balanced to ask players to equip this two skills to fight against SF sin?
100% of time immune to attacks and spells, it is obviously overpowered