Angels and paladins – how to use them? There are also discussions about them here.

What could be so remarkable about this combination? They heal, they resurrect (only once per battle, by the way)... But what else? And what does light magic have to do with it?

They have good speed and initiative, deal good damage, and with the support of light magic, they will become a truly formidable force. Thanks to the light, they will move more often, hit harder, and take less damage. The opponent simply won't be able to do much... In general, Haven is good for massive, fast attacks, especially when the hero has leveled up in magic.
P.S. In the late game, Haven will show everyone its strength.