5 black dragons, ~90 black knights, zombie wife, +15% physical boots, some intellect items since I was a mage. I had no ice shards ability (I only use zarock's poison spit, glot's armor and rage drain and timeback, sometimes ice ball, I found all other abilities quite useless to a mage since they are too weak or expenssive rage wise).
it goes something like this:
1. round magich shackless on skele archers, stone skin BK's (enter battle with 20 rage at least), then just wait for bone dragons to fly in, attack them with BK's so to block entry with BK's. Do what you want with BD's as long you have timeback on maxto bring them back next round, you are probably going to use them to finnish those bone dragons so karador will cast necro call next round
2. round. timeback black dragons if you lost any, if not, and if you are full of mana, and you should be, demon portal on good place, block entrance further or place it where you will be blocking (standing on) some dead enemy stack later on (you should have demon portal spawning 3-5 lvl units and with 7000+ leadership by now) and phantom BK's (they become targeted in 99% of cases, thus saving your BK's (notice that with boots + stone skin BK's have 85% physical resistance, so enemy does zilch damage to them, 500dmg at best with his 100 BK's, witch you will now be hitting with your phantoms and then with your real BK's, reducing their number from 100 to preferably ~70 in one round

)
use BDs carefully, try to park them near necros if it is safe, shower those ekleton archers in the process)
3. round. demon portal again, mana spring on phantom BK's (by now ghosts, BK's zombies etc. are all near them and will hit them, kill them all), your demons come from previous portal. use poison spit on enemy BK's to reduce their attack and give them nice 100dmg per turn next four turns, reduced attack is the key here), kill bone dragons ofc, this goes for every turn
4. turn. magic spring on demons from first portal, or wait for the new ones then magic spring them. (if you don't have stoneskin maxed out then you will have to stoneskin your BK's again!) Use rage abilities depending on situation you are in, you can timeback something again or cast ice ball to distract something/lure enemies away (if you cast it near crystal some stacks will move towards it, zombies and skeletons probably), your BD's are playing with skele archers and necros, it depends on their movement, but you should have killed them off by now (archers)
.... later rounds keep your BK's stoneskinned, use magicspring and demon portals (cast them on dead stacks), when you reduce enemy numbers enough, start casting broken armor, have your black dragons pick on the crystal, your BK's and demons picking off things arround the map, karador should be out of mana by now from resurecting dragons. If you placed magic springs well you should even have enough mana to "sheep" somthing anoying or cast more demon portals
You could go with demons stack instead of BK's (demons demons

furious ones

) but you have to take care of ghosts and vamps as quickly as possible then, also stoneskin them asap and magic spring them, then divine armor them, then eventually teleport them in the crystal, keep them buffed up, timeback them, whatever, just keep their numbers high, use their pentagram (use gift to repeat), I found that only 50 of them in pentagram do cryticals like crazy (5000+ dmg for only 50 of them!) if you phantom them you can cast pentagram and more demons which stay after phantom is dead etc.
using lot's of units in these kind of battles is complicated. Less is more. it is easier to buff one stack than 4 stacks and you know what is going to be attacked, by whom etc. even you, in this case with karador, don't kill bone dragons, karador can't cast hypnotize on BD's or BK's. He can cast "doom", but I never saw him do it, perhaps he dosen't have maxed out doom?! (if however he does cast doom on BK's then I guess you have to dispel asap

)
I had many problems in KB AP and in KB TL until I started tossing units, bringing only essential ones (later in the game ofc), for example, for suppressing items: demon portals and single BD stack and you are good, just be carefull, I bring green dragons (for invissibility tactics), demons, BD's and BK's. I have stashed ancient vamps and red dragons, so I usually go with two stacks on battlefield (one BD stack can win almost any battle, probabbly it can win every battle, but it is too slow and frustrating sometimes, I can't get my self to play 20+ turns every battle, brainstorming portals and traps to hide the dragons etc. but it is doable. I finnished that tournament in the castle as a level 15 mage, 3 BD's only against level 30 dragon (finnal battle), but I lost one dragon :/ demon portal level 3, trap level 2, magic spring lvl 2, stoneskin lvl2 (I cast magic spring and stoneskin on summons when facing all physicall units, saves me from casting another portal later and doing something else instead).
in KB AP single BK stack with mordor as companion and a shard + mask you are unstopable, just cast elvin to res BK's, and if you have 100+ BK's later on, they criticall 20.000+ dmg all the time (with mage! I can't imagine what they do with warrior class

)
hope this helps