Gandalf the Grey :
1. Magic Blast
2. Thunder Sword
5. Ride a horse (not Shadowfax yet)
7. Glamdring : Gandalf receive Glamdring, an old Elvish Sword that break the ennemies forces
Passive ability : Gandalf get permanently +30% damage against all units, and +50% damage against orcs and gobelins. He has 10% to make splash damage against ennemies
10. Gandalf call his old friend Gwaihir, Lord of the Eagles. Gwaihir is temporaly summoned to the Battlefield.
Gandalf the White
1. Magic blast
3. Mithrandir : Gandalf is known to be a hopeful everytime. Nearby allies get +100% armor and resistance to fear. Passive ability.
5. Shadowfax : Gandalf call his friend, the Lord of the Horses, one of the Mearas. Shadowfax has a +50% resistance against spearmens.
8. Istari Light : A powerful beam of light thats hit a small zone. Stun nearby units for a while.
10. Word of Power : Gandalf unleash his power and surround himself with all his magic power. All nearby units are blasted by his power (same as classic WOP) and are temporaly stun if they survive.
That's all i have to tell, Gandalf the master challenge / corrupted are perfect for me
PS : if Gandalf become Gandalf the White, he will get Glamdring anyway
I have a second suggestion about the Eagles : replace the 2 randoms eagles summoned with Gwaihir (i mean the Gondor/Arnor palantir Power) by his brother Landroval and by Meneldor (who could get a fast fly ability ?)
That's all for me