It works exacly like lifesteal. If you have 10% spellvamp and deal 400 dmg with one spell. 400*0,10=40 That means you get 40 HP when you do this amount of dmg.
Fourty.
The number 40 is spelled forty.
40= forty
forty
Forty.
I would recommend 20 Spell and Trap Cards, and 20 monster cards, or if not, you can have any amount of Spell Cards, as long as there are 40 or under, because 40 cards are the number of an official deck
Cuarenta
quarante
40 dollars is spelled out 'Forty dollars.'
30 is written as "thirty" 40 is written as "forty"
40 -> Quarante 60 -> Soixante