Chaos structures.

Yuriy, regarding the topic, I also love Hydras :) They take down heroes in one hit, can be teleported, and resurrected. Low initiative is even an advantage for someone who wants to remove immunities from the enemy first. And as for the speed boost, that's not the main goal of building a 4th-level dwelling.

Ruslan, you keep confusing me. Dima Streinger brought 300 ballistas to PS and also put on a show. ;) However, this is more of an exotic strategy than a guaranteed one. Try to find a Town Portal for Chaos, and you also need to gather quite a few Hydras to make it interesting (let's forget about PowerSpot and Bizarro :D).

Regarding speed. And who are you going to fly with? With Ifrits without Hydras? Then it's unclear what you're going to fight with. Chaos doesn't have anything to boost its speed with.