Sun Priest's Scorching ray is unimaginable unbalanced

There is a monster type, a floating mage called sun priest that does a scorching ray, it's fine, it deals continous damage, fine.
What is not fine is it's range, it has 3 screen long range

IT HAS 3 SCREEN LONG RANGE of scorching ray, basicly cant run away from it. It killed me 3 screens away because i couldnt run away from it's infinite range. Is that fun?

In theory, player is supposed to go behind this monster, when it casts beam.
Or hide behind some wall or pillar.

That works in Act 3 in Temple of Kopec, because monsters there are sort of balanced.

But in maps it gets wild, as monster packs are generated randomly. You can easily have 3-4 priests of the sun in the open location, and even if you go behind the one, others still will burn you down.

Pack compositions in maps need to be fine-tuned, with the location properties in mind.