Necropolis is considered one of the strongest castles on random maps in many scenarios. Often, to maintain a good pace, it's necessary to capture Dragon Utopia early. One way to do this is with an army of 270 Skeleton Warriors, 20 Zombies, Galtran with Expert Defense, Earth, and Advanced Attack (which can be replaced with Bloodlust magic). In the spellbook, have Shield and Stone Skin.
The point is that it doesn't always make sense to bring Wyverns and Angels to Utopia, as antimorale is possible, or there may be fewer than 5 Angels. This always leads to unnecessary losses, while sacrificing Skeletons can often be beneficial to gain control or acquire good artifacts. The battle takes place on neutral ground; on Necropolis ground, everything is the same, only upgrading the Skeletons is not necessary. On grass or underground, the turn order of the Dragons will differ. I suggest experimenting on your own.
Dragons make their first moves differently, so in the example, I will only show one of the options. Attack/Defense 7-7, no attack but with Bloodlust. There should be enough mana for 8 rounds, and the magic power should be at least 4, so that spells are cast on the Skeletons in each round.
Deployment: 265 Skeletons, 1 Skeleton, 1 Skeleton, 20 Zombies, 1 Skeleton, 1 Skeleton, 1 Skeleton.
Round 1: Black and Golden Dragons attack the Zombies. Red and Green Dragons attack the single Skeletons. With a single Skeleton, we remove the retaliation from the Green Dragons (sometimes it's not possible to reach them, then the first attack is on the Red Dragons), we surround them with single Skeletons, and the main stack attacks them as well. Cast Mass Shield on the troops.
Round 2: Golden and Green Dragons attack the single Skeletons. Cast Stone Skin, and attack the Golden Dragons.
Round 3: Red Dragons attack with a burning effect (sometimes they don't do this). Cast Bloodlust, and attack the Green Dragons.
Round 4: And so on, we maneuver and make sure that the Skeletons are always under the effect of a spell.
Result: 57 Skeletons survived.