Enraged Kurandara (EK) costs 8 orbs of power to craft, the same as Zuul;Goth, Ctharrasque, and Maelstrom Dago’Nath. But the those three all have insta-kill spell, while EK has just a decent damage-all spell - if its mana cost is 25 or so, not 35. Even when there’re lots of doomskulls on board, its spell still does less damage than diamantina, let alone later generation of ultra dragons.
Invulnerable was once EK’s shiny point of worthiness. Back in times only EK, Leonis Tower, and 6 Dooms have that trait. But now there are a whole bunch of immortals that are also invulnerable, and much cheaper to get. And MD is invulnerable, too.
Curse all without spell is the only thing that only EK can do. But does it worth 8 orbs of power? Since a lot troops can curse (plus another debuff) 1 random enemy on match-4, 40% curse (and only curse) all on turn beginning may have less value than it looks.
My suggestion:
Change its third trait to Enraged Manifestation: Gain 5 to all skill points and enrage myself when mathcing skulls.
This effectively makes it always enraged. It is Enraged Kurandara, after all. To help it survive as its new role of skull damage dealer, change its first trait to some decent skull damage reduction like stoneskin (50%), or some good skull damage reflection like 50%, or some good dodge chance like 50%. The later two step on toe of other legendary traits, but hey, EK is a big boss, it deserves better than usual traits.