Sylvan vs. Necropolis

Why aren't you paying attention to the Lord of Cold? It deals more damage and freezes enemies, its skills and spells are easy to acquire, and it's particularly effective against Necropolis. The downside is that the Ice Shield isn't the rarest artifact. As for switching to Necropolis, I think you should do it as soon as you have dragons, because by that time, the Necropolis will have accumulated some undead, and your existing vampires and zombies will be taken out by Ents and shot by archers. Your melee units will handle the rest. By that time, the Necropolis won't have built up its guild, and even if it does, it might be at the expense of summoning (meaning it will summon fewer undead). And even then, it's not a given that it will build the guild. If you take Wisdom with Attraction, you'll be able to summon elementals a couple of times, which will help you take out the zombies and vampires. I'm interested to hear the opinions of Necropolis fans, because I don't like them, and that's why I might have described their development model incorrectly for weeks 3-4.