We Can Fix That with Data

Blizzard’s been taking advantage of the Wrath of the Lich King beta to make major changes to their core RPG. This is a nice situation for them — they get to iterate, they get tons of player feedback, people are actively playing (unlike most games’ test servers), and they don’t destabilize their live service.

One of the latest changes is a change to the way that mana costs are calculated. They’re switching from the normal fixed costs for particular spells (Generic Fire Nuke (Rank 1) costs 17 mana and by god, it always costs 17 mana) to scaling percentage costs (Generic Fire Nuke (any rank) costs 10% of base, unmodified mana no matter what).

A few players are excited, but the majority are unhappy about this because it does away with “downranking” — casting a lower-level version of the same spell because it costs less mana and is more efficient for your purpose. Healers do this quite a bit. If I know that my target only needs 1k HP healed, why should I spend a ton of mana to cast my max-rank heal that heals for 3k, when I could cast a lower-ranked version that heals for 1k and costs much less mana? Smart healers usually play with a couple of different ranks of several of their spells on their cast bars. Hey, it’s strategy!

Usability-wise, in World of Warcraft, where your spellbook displays all the old ranks, it’s not hard to sit there and do the mana-per-HP healed calculation yourself, or you can use a mod like DrDamage to do it for you. (People downranked in Shadowbane too, but they had to rely on oral tradition to get the slash command to access those “obsolete” spell ranks.)

Loss of the strategy of downranking aside, it’s a good change for the designers, in terms of using their time efficiently.

When I’m costing a spell the traditional way, I’ll use a spreadsheet that says something like “okay, this is a level 10 spell, and at level 10, you should have about this much mana and this much mana regen, and I want you to be able to cast this spell this many times before you run out of mana.” I’ll have to do that for every rank of the spell, taking into account how much mana and regen I think the character should have at that level. And later on, I may have to revisit those numbers once I mine the character data to confirm those expected mana values — if that data is available to me.

Generally speaking, I want that number-of-times-cast value to remain consistent as the character gains spell ranks, because it fits the player’s expectations — a lowbie spellcaster knows that she can kill a certain number of mobs with Generic Fire Nuke before she has to rest, and every time she gets a new rank of Generic Fire Nuke, that should remain the same as before. In other words, her downtime shouldn’t fluctuate dramatically as she advances, because downtime is a defining class characteristic.

The percentage cost model makes my life a lot easier. I don’t have to figure how much mana I think you should have at that level, and I don’t have to check the character data to confirm. I just say that I want you to be able to cast Generic Fire Nuke about 10 times before you run out of mana, so I say it costs 10% of your mana. DONE. (Okay, it’s not quite that simple because I need to account for mana regen, but I’m still DONE in a lot less time.)

Now, this breaks down a bit if new spell ranks aren’t granted quickly enough. Lowbie Spellcaster will find that she has to rest more often, killing the same number of mobs, because Generic Fire Nuke does less damage relative to the content she’s doing, so she has to cast it more times, but she can’t cast it more times because it still costs the same percentage of her mana. Theoretically, with traditional fixed costs, if her mana pool was scaling at the same rate as her other stats, she’d be able to cast it more often before resting to make up for doing less relative damage. (However, this means that her mana pool needed to scale properly … but math is hard and it doesn’t always work out that way.) And she still feels slightly less powerful with every level that passes without a new rank, because she has to cast more often.

The thing is, stairstepping is required to make advancement feel meaningful. I wouldn’t do percentage damage to make up for that problem. Damage is usually figured as a percentage of the intended target level’s HP, same as the traditional way of doing mana costs. The Generic Fire Nuke I intend for Lowbie Spellcaster to use at level 10, versus level 10 opponents, is probably supposed to do N% of the average level 10 mob’s health. If Lowbie Spellcaster use that rank of Generic Fire Nuke against level 12 opponents, it’ll do less relative damage. But this is the way it should be. It motivates Lowbie Spellcaster to get off her ass and level to earn the next rank, same as Lowbie Fighter should be motivated to level to use a new sword. When they get their respective rewards, they feel like they’ve accomplished something.

Going back to WoW’s situation: the loss of downranking, to be fair, might increase workload because the designers may want to build and maintain abilities that perform the same purpose (like small, low-cost heals for that poor shaman in the thread I linked). But in the long run, percentage mana costing makes their lives easier. If I were balancing an RPG right now, I’d be inclined to make the same decision.