Beasts are a very strong addition to the army and also have passive skills which can be used to great effect, information on the passives can be found here.
For an attacking player the Pegasus is simply awesome. As an example of this, there is an event called “lake leviathan” shortly after the beasts were released I was trying to solo lvl 4, I killed it with Pegasus with ease but without the Pegasus the monster would defeat my army with 20% health remaining.
Provides a brilliant defensive bonus to your front line but the front line needs to be big for this to take effect (it’s getting reduced in number before the beast uses its skill) easily the best beast for defence.
The dragon will get more kills on its own and the damage is ok but when compared to the Pegasus and Panda it just does not hold any ground at all. Not worth using unless you’re server has agreed on a beast fight for crown or something similar.