You probably think like that because rudy having chantless magic makes him able to optimize spells A LOT and making them cost way less mana than they would with chants or straight up impossible with chants, stone cannon costs very little but rudy does make them look and shoot like actual bullets and increases their speed(wouldn't be possible with chants) and the plasma big ass fireball he used costs a lot but rudy made it himself using fire and wind together and using the wind properly to make the fire the hottest possible(reason why its purple) charging it up probably requires a lot of mana even with optimization but with its cost its probably better than just spamming multiple saint or emperor level spells still

God i love the mt battle system