Hashut’s Blessing:
From the little context given, it does sound possible the Stormcast Eternals warscrolls were being used incorrectly, mostly with the Celestant-Prime. Step one is to go to the Games Workshop website an download the most recent version of the warscrolls for your opponent’s army (not just the ones listed here as I imagine their force has progressed in the nearly 2.5 years since) - that will not only help you make sure units are bing used as they should be, but also give you a better idea of what threat each poses and what your best plays will be. As someone else has ntoed, it’s best to make sure that the force is legal in the same way yours is (note: You can’t use the same artefact twice, so no double Crown of Conquest - that may be where we’re in the second edition of Age of Sigmar now though).
For your Chaos Dwarfs, I’ll assume you only have these models (for now). The Legion of Azgorh is good at shrugging off wounds and dealing heavy damage at range - for the most part, ignore the existence of the Celsetant-Prime and target the rest. You can target 100% of your army against literally two-thirds of theirs and remove them fairly swiftly, then focus what you have left on the 1/3 of an army in a single model (if you want to go for army annihilation over objectives).
Having just looked at the rules for the above, the models are pretty tough, but target selection becomes quite obvious. I’ll focus on the units for a moment first: your Bull Centaur Renders and the Taur’ruk want to avoid the Protectors since they get extra damage against you - shouldn’t be too hard since they are slow and you are much less so, so you might as well target something else. It’s be easy to smash apart the Liberators (even if they have Stormshields) with the four bulls bearing down on them, but that’s 340pts for 100 - better to target something much juicier, like the Retributors. Sure they are tough, but you put out a lot of attacks, have some rend, have the bounceback from Spiteshields (and as noted below, more attacks at you means more bouncing back at them) and do have the advantage of the character as well, not to mentioned the massive increase in damage if you charge (and you should be able to) and the Taur’ruk’s Command Ability allowing for re-rolling To Hit rolls of 1. Besides which, your troops can handle other stuff at the same time.
Protectors are more resilient to shooting, so there’s no use wasting your time firing at them. Instead, feel free to attack them with your Daemonsmith’s magic and bog them down with the Infernal Guard Ironsworn. After all, they can tank pretty well, especially with our Allegiance Ability (Blackshard Armour) and they will also excel at taking them down due to the bounceback of our Spiteshields - more attacks heading to us, means more attacks bouncing back at them Add to that (and this goes for the Bull Centaur Renders above too) the lovely fact that the Spitehsield bounceback is a mortal wound and suddenly their good armour isn’t helping them. You still have more wounds than they do as well and you can always support with your other models if necessary. Again, your magic will come in handy here, combinations of Fireball for direct damage and Ash Storm to protect your own guys (or slow down your opponent if they are out of position).
Meanwhile, you have two units of Fireglaives and the Deathshrieker for picking off the Liberators (shouldn’t take too long, especially with the double bonus to Pyrelock Weapons since your post) and the Knight-Venator. Deathshrieker first turn should go for the Liberators before all other attacks to get a slight bonus, the Fireglaives should try to remain stationary where possible, and your Daemonsmith should always be near the Deathshrieker for the bonus to its attacks (+1 attack leads to potentially +3 damage, after all, and you don’t want your Daemonsmith ont he front line. The long range of Ash Storm, the low number of models to block lines of sight and the decent enough range of Fireball [considering most of your army will turtle and pull your opponent towards you] means he shouldn’t be out of position either).
That leaves just the Knight-Venator and the Celestant-Prime untouched. Except we have the Knight-Venator as a secondary target anyway and to boot, Burning Skies will help to hamper his effectiveness - every time he moves more than half his base movement, he risks taking mortal wounds (again, bypassing that great armour save and it doesn’t cost you anything). It may well be that your opponent ends up not able to support best or be in range (despite the massive range of his attacks) of a key target or reach an objective - alternatively, they may well ignore it, but they’ll occasionally lose one or more wounds. In fairness, you will need to be wary of Star-Fated Arrow (looking at your Taur’ruk and Bull Centaur Renders), but there’s not much you can do about it on the first turn, which is probably the time your opponent would use it (they have the range and no reason to hold back with it, after all). Some concentrated fire and magic will take the guy out quickly enough if you take out easier targets first (or use attacks of opportunity - if he’s in range of a unit of Fireglaives and the Liberators are a move-and-shoot away, feel free to try to cripple/eliminate him).
Now for the ‘Big Bad’ ™ Celestant-Prime. If he’s not on the board for turn one, yes he becomes more potent, but it also means you aren’t threatened by it too much for a turn (and he may stay up there for longer to maximise the use of Ghal Maraz). Either way, focus on the rest of the army a little first - it shouldn’t really take too long to eliminate a unit or two and every time a unit of yours frees up, you can add it to destroying the rest of your opponent’s army or try to piecemeal approach the Celestant-Prime. The Cometstrike Sceptre and Orrery of Celestial Fate means he has some ranged threat, but his primary impact is in combat - shooting and magic will help here (Ash Storm will slow him down, meaning you might avoid direct combat an extra turn or two). Ultimately, he’s very offence based, but only has 8 wounds and a 3+ save, with no special rules for making him tougher.
Apart from the Trample and Gore attacks and the Fireglaives’ close combat attacks, everything your force has a Rend of -1 (and the Taur’ruk has -2). That makes his saves only a 50-50 chance of success and with only one re-roll per turn, against a host of attacks, shouldn’t be too much trouble. Extra ways to deal with him - give your Taur’ruk Grotesque as your General and charge straight in (then support the Bull Centaur Renders after - personally, I think better to treat them as his entourage and remove the Retributors first) and/or fire the Deathshrieker at him for a couple of turns (remember, he doesn’t need to be visible