there are three different kinds of spells we here call them mantras, one is the darker one if failed goes back and kills and destroys the caster and the one who ordered the casting.
The second one is purer with no side effects but it is not a short cut way it takes long time to practice and maintain more purity,but its more powerful.
the third one is not cast directly but the energy is stored in swords,mystic arrows spears,armours.(these were given to the kings in india that was the main reason why kings had a guru king is dependent on the yogi power of guru and rishis)
There is always been a conflict between these three. Its like day,twilight and night.

but modern civilisation is destroying all the powers