You still had to pay for them, to create them, but it let you be really creative with it. For instance, I created a "Panic button" series of spells, that would make me invisible and heal me at the same time. Or at higher level, Invisible, heal, and speed, so you could easily make an escape from a tricky situation. Or lets just say you needed some time for your mana to recharge, your not in danger, but you are running low on juice, you could make a spell that would slow the enemies, or make you invisible/invulnerable, and increase your mana recharge rate. Or if you were attacking, you could combine a health drain, with heafty damage. You could drain a lot of health if it was only for one second... so then you could follow that with a lot of damage right behind the drain, and make a one-shot-one kill spell. It was all about the creativity.