True magic users were rare during the Second World War. Fortunately most of the Axis wizards were merely schooled in ritual or used artifacts collected by the Ahnenerbe. True magicians were categorized by their ability to create virtually any effect using magic on the spot without using rites or methodical magical procedures though the range and duration of their spells varied.
There were several mass magic workings attempted during the war. Soviet operatives attempted to summon and inflict waves of gremlins on the Luftwaffe. English druids manned the white cliffs to send lightning bolts and hail at German bombers raiding Britain. The Ahnenerbe used several massive rallies held for the Party to attempt to conjure incredibly powerful beings to aid the Reich (including the Aesir and Vanir). These rallies were thankfully disrupted by Allied agents and spellcasters.
Magic also had several hard and fast limits.
1) The magician always has an object or action to cast their spell. Whether it is speaking a lost language, composing a quick rhyme or waving a wand, their powers are quite limited or nonexistent without these focuses.
2) Conjured objects that appear out of thin air are not permanent. The stronger, or larger the object the more temporary it is. A magician conjuring a nearly invulnerable shield might find it only exists while he is concentrating on it. This prevents our Axis foes from conjuring valuable strategic materials. Creating radioactive materials out of thin air seems to be impossible thank goodness.
3) Enchantments are spells that magnify or reduce the qualities of animate or inanimate objects. They last longer than conjurings but may still need maintenance spells from time to time or rare elements or artifacts to function. An example would be the magic sword able to cut through steel, that needs to drink the blood of the innocent to remain sharp.
4) Living creatures can be conjured. Aside from the smallest and most innocuous animals these are limited to a few minutes of existence at most. Some entities can be summoned which is completely different. Summoned entities remain until they are dismissed or rebuked, requiring another spell. They also can be very intelligent and dangerous.
5) Time travel appears impossible.
6) Raising the dead to true life is impossible. Vampires, zombies and animated skeletons are very possible. Don't be fooled.
7) Cold iron (and to some extent steel) will disrupt the function of magic and usually effect magical creatures, especially those summoned. More advanced mages can compensate for the effect though their spell power may be reduced. A dragon might need to be killed with a sword as lead bullets bounce off it and flames just keep it comfy and feeling loved.
A magic user can use his magic to deal damage as a creature of equal levels out to nearby range. They can cast spells affecting the six attributes of a victim directly and requiring saves. Usually a magic user can affect one attribute per two levels. So a 2nd level magic user might decide they cast illusions to befuddle people and affect their dexterity by tripping them up running int walls etc. At 4th level they might broaden the effect of their illusions to play on a person's inner fears and affect Intelligence or Charisma. Inanimate objects in general must be affected using spells against strength or constitution. The referee has final word on what magical effects are possible. A magical effect can create a shield with armor points equal to double the character's level and affecting him and nearby characters.
The character makes a test vs. Intelligence for the spell to take effect. The rules for powerful adversaries should be used.
A magic spell can affect a number of 1 HD or lower creatures equal to the magic user's level if they are standing in a group (like a machine gun nest).
A magic user can create or summon a living creature with a level half that of the magic user's and may have an additional power (see some of the super powers I've already written up). Imitating a super power is also possible with the referee's okay.
The magical power available to a character is represented by a usage die (what else?) The die is equal or less than the magic user's level with a minimum size of 1d4. If the magic user chooses to roll the die and it comes up 1 or 2 it is reduced one size as normal and the spell backfires doing damage equal to the caster's level to the caster or a friend. When the die is 1d4 and comes up 1 or 2 the character in unconscious and takes double damage. By rolling the die the character may cast a spell as if he were one level higher.
Using artifacts or rituals don't have a chance of backfires. The spell simply doesn't work. There is no usage die involved.