(Hero - Rogue) in Heroes 4

I simply replied that mana is easiest to obtain in the Chaos Castle, and there was no mention of your "one, two, three" points at all.
P.S. There's no point in continuing the discussion, because you used the magic (and, frankly, overused) word IMHO. It's become so common on the forum (((

Leshy, if you want to switch to a formal tone, go ahead. You "simply replied that mana is easiest to obtain in the Chaos Castle," and I simply replied with the reasons (one, two, three) why it's best not to obtain it there. The Energy Vortex is, of course, a useful thing for a mage. But allow me to point out that a rogue initially has less mana than a mage, and that will always be the case. And the Vortex itself isn't a panacea, as it only increases mana temporarily.

Why would a rogue need to be a mage?

That's exactly what I'm saying. And, most importantly, the desired bonus from Chaos magic (+20% damage from fire spells) will be difficult to obtain, as acquiring magic, especially this specific type, is problematic. Here, there's another, completely effortless, but no less sensible option: making a Ranger. +10% to ranged attack. At the same time, the hero improves combat skills, magic resistance, and can now definitely wander around the map alone.
Whether the player will have time to level him up (considering that the rogue is not the main hero) is another question. This depends on the map and the overall situation.