Comparing Stellarix to Zuul and/or EK while only looking at mana cost is a bit disingenuous, even if unintentional.
Starting with Zuul— short of you carrying a curse option AND a way to then impose status effects (therefore almost making Elementalist a necessity but that’s its own topic), ZG isn’t going to be impacted. Adding the freeze all and skull spam on cast is still a huge tempo advantage.
EK has at least a path to curse AND is a hard counter to Zuul’s lethal damage AND is Invulnerable AND has bonus mana on red matches. Used properly, EK’s doomskull convert is the 2nd half of the ZG spell and is another tempo win.
You can get both via Orbs of Power-- a “currency” that has never been easier to acquire than it is today. The barrier to entry is nowhere near what it once was.
Now Stellarix-- no insulation from status effects as has been mentioned further in the thread. Wand can provide bless, sure. Wand also in the hands of the AI introduces the randomness of which side Wand will cast. If you specifically target Stellarix/Wand via status effects (and looking at a curse option for a bonus), you can leave Wand in a place where, at minimum, AI wand would need to hit bless on 2 casts (one to remove curse, one to then actually cleanse) and that’s assuming you never had a chance to take another turn-- which if curse/freeze were both applied, you’d get at least 1 more attempt to refresh the debuffs.
The cost for Stellarix, lack of protection and all, is significantly higher than any of the troops listed above. There’s 9 prerequisites, 6 (the ‘regular’ dragons) of which are directly impacted by RNG and the remaining 3 (the weapons) contingent upon the first combos of RNG.
With a much more expensive cost of entry with cost meaning time and/or money, Stellarix should be on its own level of power.
Going to potentially disagree on the answer being to revert PvP to 7.3 and offer a different suggestion. Players are running Wand/Stellarix/Takshaka, etc because it’s really fast on offense. On defense, it’s not nearly as strong unless you’re trying to fight speed with speed.
Right now, the risk/reward just isn’t there to change to a team that could counter the “meta”. There’s just not enough VP on offer to make it worth the time to craft a counter so instead, you try to outrace the meta and, especially in the buffed zones, you’re going to fight a losing battle. Losing leads to frustration which leads to calling for nerfs and solutions that won’t actually answer the real issue.
Make the risk/reward fall in line and you’ll see the rest of the pieces fall into place.