The Speed trap - an assessment of Speed in DestinyQuest
6 May 2014 at 1:49am
I love DestinyQuest, but one thing that bothers me more than anything about this game is the Speed trap.
You always need more Speed. Speed does far more for you than any other stat. Indeed, a point of Speed is usually more important than any other consideration when selecting gear.
That's a shame, really. All that fine gear, with interesting abilities, but do those items keep me on the speed treadmill? No? Gotta dump 'em.
Why is that?
Let's look at the following table, which analyses how likely you are to win combat rounds for a speed differential, all other things being equal.
Spd diff| Rounds you win for every round they win
-5 | 0.06
-4 | 0.12
-3 | 0.22
-2 | 0.36
-1 | 0.60
0 | 1
+1 | 1.66
+2 | 2.72
+3 | 4.80
+4 | 8.52
+5 | 16.93
See, if I fall behind even by 1 Speed point, the enemy are winning 1.66 combat rounds for each round I win. If I fall behind by 2 speed points, they are winning 2.72 combat rounds for each round I win.
The only item benefits that comes even close to the value of Speed points are those abilities that allow you to 'flip' a combat round from their victory to yours. Abilities like trickster, deceive, overpower, brutality, and command. How do they stack up?
Suppose I am at -1 speed to you. You get 5 wins to my 3, so to even the score, I'd need to spend one 'flip' ability every 8 rounds that don't stalemate.
If I am at -2 speed? Then you win 19 rounds to my 7, so I'd need to flip every 4 1/3 rounds.
God forbid I'm at -3 speed. Then you win 48 rounds to my 10, so I'd need to flip every 3 rounds to balance it.
Spd diff| # of flip abilities you need
-3 | 1 every 3 rounds of fighting
-2 | 1 every 4 1/3 rounds of fighting
-1 | 1 every 8 rounds of fighting
So it looks like if you expect a fight to go 8 rounds of combat or fewer, trading a point of speed in favour of a flip ability on a one-for-one basis is worthwhile. If the fight lasts longer, then Speed is better.
So why is this the case?
The reason for this is the way Combat uses 2d6. Since incidences of high and low numbers fall off sharply, you get into trouble. If I have a 3 point speed deficit, the odds of me rolling high *and* you rolling low are much worse. Witness what happens when we replace 2d6 with 1d12:
Spd diff| Rounds you win for every round they win
-5 | 0.18
-4 | 0.26
-3 | 0.36
-2 | 0.51
-1 | 0.70
0 | 1
+1 | 1.42
+2 | 1.99
+3 | 2.75
+4 | 3.80
+5 | 5.52
Spd diff| # of flip abilities you need
-3 | 1 every 4 1/4 rounds of fighting
-2 | 1 every 6 rounds of fighting
-1 | 1 every 12 rounds of fighting
Much better. Also, the break-even point for 'flip' abilities is with fights that last more than 12 rounds, not 8 rounds.
If you want to play with it more, the following principles apply:
* Single dice work better than multiple dice added together, because a flat distribution curve is most favourable to those 'left behind' with speed.
* Changing the size of the dice matters. The smaller your dice, the more painful speed differentials will be. The larger the dice, the less painful.
Side note - if you look at how Dungeons & Dragons works, they use this mechanic in to-hit rolls. They use 1d20, but the same analysis applies.