How does spell damage work?

I am asking this question, because I am currently using the Champion Set, which gives +75% damage bonus, which I assume affects spell damage as well. However, someone suggested that I use a more spell damage focused build, because they thought that my Champion Set does not do as much damage. How is that the case? For example, the bow Torrential Tide that many people recommend using only gives around 200-300 raw spell damage, which seems really low given that around my level, 88, my spells do thousands of damage. Can someone please explain this to me?

 

Here is a thread that goes into the full details of how damage is calculated, including how spell damage works. If you don't want to read the whole thread, the short of is that percent damage is added onto your spell damage multiplier, while raw damage is added on and multiplied by the multiplier. Arrow bomb, by default, has a modifier of 160% or 1.6x your base dps. The 75% bonus damage from the champion set brings that modifier up to 235% or 2.35x your base dps. The raw spell from Torrential Tide, which has a base of 275, will become 440 after the conversion from the base modifier, and 646 assuming the 75% bonus from the champion set. For archer however, you tend to benefit more from percent damage bonuses, due to the high base damage and low spell damage multipliers (I can expand more on that if you want). The main damage bonus you would get from Torrential Tide would be the high base dps, assuming that is higher than whatever you are currently using, as well as the other bonuses that it gives to spell builds (intel and water damage, which scales with intel). However, changing out your bow doesn't necessarily mean changing out your armour set.

What people likely mean is that you can get a build that gives a great deal more than whatever the equivalent of 75% spell damage is for your current build (which is simply 75% of your base dps, before other modifiers). Using gear that gives spell damage, water damage, or just damage, you can get much higher damage than the Champion Set bonus will give. That's not to say the set is bad; 75% is still a respectable amount, and the set offers numerous other bonuses including an absurd amount of health regen that make it extremely viable until fairly high level, potentially even until endgame. Realistically, if it works there's no reason to change it unless you want to. You can plug potential builds into Wynnbuilder to see how they compare in damage, ehp, sustain, mana costs, and whatever else you might care about. It's a lot easier than trying to math it all out by hand and lets you easily swap out items to see what works.

EDIT: I just saw on your other post that you're using Az. I would probably stick with that as I doubt Torrential Tide can perform better than it without serious compromises, as both have a similar base dps with full t6 powders. However, since Torrential Tide is a water bow, it does have some notable perks for a spell build that might make it easier to build a well-rounded spell build with, but I doubt it would really make a major difference. Az is absolutely viable until the endgame, though the damage does obviously fall off at a certain point.

 

Thank you so much! I think you answered my question:) Az is great, but it requires me to put 80 points into dexterity, which makes it hard to use any items that require other stats that might be good, which is sometimes an obstacle.