How to attack stealthy astral mages?

[Psycho]

Micah is right, but those are all too expensive ways to attack several shadow seers who cost 180 gold. Fires from afar will probably hit only one or not even one, flames from the sky should kill half of them but it's too expensive. They attack in small groups.

They de-stealthed on my seraph, took my sickle and I want my revenge!