One of the most important spells when it comes to fights. When fighting small and medium monsters/thanes while flying those monsters/thanes become incapable of moving against you. Large monsters will be able to approach you.
Flying vs Land(small/medium): Flying can aproach Land based on speed. Land cant approach Flying and can attack Flying only when Flying moves within Land's range.
Flying vs Flying: Flying can approach Flying. These fights are treated just like Land vs Land fights. Both approach to their optimum distance based on comparison of speed.
Flying vs Land(large): Flying can approach Land. Land can approach Flying. These fights are treated the same as Land vs Land fights.
Keep in mind that flight works thane vs thane.
If you are on the ground and go for the first blow against something flying you will never hit unless you have an item or spell that can hit from 17 distance. Its important to learn the distance of both your item and the reach of the monster you are fighting.
Another point to be made. Do not land or fly in a room with a monster. If its able to approach it will do so to a very close distance.
The overwhelming benefit of flight is that you can control exactly what distance the monster you are fighting stays at based on your own attacks. Learning what combination of monsters and equipped items produce these easy kills can make or break a person's carreer in GC.