what do skills have to do with having 40 crystals when you need 70 for one good level 3 spell?
(and no, I am not taking and learning spells that I do not use, but I also don't want to torture myself and use only dispell, fear, haste and heal trough the whole game. Look at the costs of sacrifice (only way to get some units in full numbers) lvl3, geysir lvl3, demon portal lvl3 alone costs more crystals than you can find on 3 islands if you learn a few more spells beside that, and as a mage you have to learn stoneskin, brake armor, fireball, fire arrow, dispell, heal, fear and maybe a few more).
those impossible no loss games were done using F5/F8 exploit to kite maps instead of fighting for them. While it is hard work and skill, it is still a cheat of sorts because enemy is not behaving like he was intended to. Increase of radius of enemy attack possibility by just a factor of 1 would make most of those KB masters just average players IMO, no offense. They have to get to 2000 leadership and at least one tough 700+hp unit for all their tactics to work. Without kiting maps this is impossible (for no loss game on impossible). Average idiot would be able to clear darion, scarlet wind, anchor island with a dragon or two and nothing else except fear and heal spells...
so I don't think that pressing shift + ~ and typing in "crystals 100" is any more of a cheat than f5/f8/f5/f8/f5/f8/f5/f8/f5/f8 to get the map and go where you are not supposed to go without certain level/troops etc. Now many will say that save/load is part of the game, well shift+~ is part of the game also so stfu
the sole fact that mage needs same amount of crystals to learn spells as warrior or paladin does is insane. Same goes for mage with might runes needing the same amount as warrior class to learn might skills. Mage should not need crystals at all for learning spells, or at least that alchemy skill should lower 100% on level 1, 150% on level 2 and 200% on level 3 (for mage only). Best thing would be that mage needs intellect on certain level to learn/upgrade spells, say for lvl 1 chaos spells int. must be at least 5, for level 2 spells - 15, for level 3 spells - 20. Enemy heroes with low intellect cannot spam hard-core spells that they could not learn with that intellect. This needs balance even now. Int. 10 hero spamming geyser or doing 1500 with infernal blades...has 150 mana...sure, put that in on some nightmare mode
or towards late game, not to guard a map when you are level 10 on normal difficulty.