With our 4th hit proc attacks--Fang and Claw/Wheeling Thrust--thinking about Life Surge usage gets a little more complicated. Should we save Life Surge for Full Thrust the way that we generally used to, or does it make more sense to blow Life Surge on F&C/WhT? After all, they deliver an impressive 290 potency, and they happen very often throughout the rotation.
Let’s check out the math.
If I land a Full Thrust without Life Surge--assuming that Heavy Thrust and Disembowel are both active--I end up with a raw potency of 360 x 1.15 x 1.10 = 455.4 potency. However, there is a chance that we might get a critical hit on that FT. Let’s use a Critical Hit Rate of 593, which is what we end up with using
full i180 Law gear plus one i170 Law ring and a Hive Spear. At 593 crit,
we have a 10.5% chance of getting a critical hit, and
critical hits deliver a bonus of almost exactly +50% to base damage.
So, that 455.4 potency hit becomes 455.4 x 1.50 = 683.1 potency, 10.5% of the time. A little number crunching tells us that the average potency of your Full Thrusts over time (crits and non-crits averaged together, across infinity uses) comes out to 479.31 potency.
(455.4 x 0.895) + (683.1 x 0.105) = 479.31
By using Life Surge on a Full Thrust, we get a bonus of 683.1 - 479.31 = +203.79 potency.
Next, we’ll turn our attention to Fang and Claw/Wheeling Thrust.
Base potency for a 4th combo hit with Heavy Thrust and Disembowel comes out to 290 x 1.15 x 1.10 = 366.85 potency. Potency with a critical hit reaches 366.85 x 1.50 = 550.28. The average potency in the long-run with our Critical Hit Rate of 593 comes out to (366.85 x 0.895) + (550.28 x 0.105) = 386.11 potency.
By using Life Surge on a Wheeling Thrust or Fang and Claw, we get a bonus of 550.28 - 386.11 = +164.17 potency.
Now, let’s put those numbers to use. Obviously, a crit Full Thrust is better in absolute terms, but the real question is: How long, if at all, should we be willing to save Life Surge for Full Thrust for that pairing to be worth it?
Consider our rotation: HT - ID - Dis - CT - 4th - Phleb - TT - VT - FT - 4th - (repeat)
Now, if Life Surge becomes available between Phlebotomize and Vorpal Thrust, there’s no question that we’ll want to pair it with FT. But there are two other, more complex situations: we can potentially decide to use Life Surge immediately after Chaos Thrust, or after Full Thrust, if it is available at these moments. I’ll label these two decision points (A) and (C).
HT - ID - Dis - CT -
[Life Surge? (A)]- 4th - Phleb - TT - VT -
[Life Surge! (B)]- FT -
[Life Surge? (C)]- 4th - (repeat)
One thing I’ve noticed while practicing and using the rotation is that, at a 2.4 second GCD length, each Life Surge will be available to buff an attack exactly one GCD later in the overall rotation. (This is only for a 2.4 second GCD. More on that later.) Thus, if I buff TT-VT-[Life Surge]-FT-4th in my opener, LS is next available for TT-VT-FT-[Life Surge]-4th. There is, in other words, a 21 GCD gap between Life Surges becoming available, and this slightly staggers the GCDs we can pair it with.
One approach would be to pop Life Surge with the soonest possible Full Thrust, Wheeling Thrust, or Fang and Claw, regardless of whether we’re at point (A), point (B), or point (C):
HT - ID - Dis - CT - 4th
Phleb - TT - VT -[use Life Surge (B)]- FT - 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT - 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT -[Life Surge becomes available]-[use Life Surge (C)] 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT - 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT - 4th -[Life Surge becomes available]
HT - ID - Dis - CT -[use Life Surge (A)]- 4th
Phleb - TT - VT - FT - 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT - 4th
(entire pattern repeats)
A second strategy would be to only use Life Surge immediately before or after Full Thrust. That is, we could pop LS at points (B) and (C) without ever popping it at point (A). After all, maybe point (A) is close enough to Full Thrust that saving Life Surge for a few GCDs is actually advantageous.
HT - ID - Dis - CT - 4th
Phleb - TT - VT -[use Life Surge (B)]- FT - 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT - 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT -[Life Surge becomes available]-[use Life Surge (C)]- 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT - 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT - 4th -[Life Surge becomes available]
(entire pattern repeats)
Last of all, we could use Life Surge exclusively with Full Thrust, on the assumption that it delivers enough added potency to be worth the wait every time.
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT -[use Life Surge (B)] 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT - 4th
HT - ID - Dis - CT - 4th
Phleb - TT - VT - FT - 4th -[Life Surge becomes available]
(entire pattern repeats)
In the first case, across the course of 70 GCDs, we end up with one LS+FT and two LS+4ths. That’s a bonus of 203.79 + 164.17 + 164.17 = 523.13 potency.
523.13 potency / 70 GCDs =
+7.47 potency per GCD, or
(523.13 potency / 70 GCDs) / 2.4 seconds per GCD =
+3.11 potency per second
Under the second approach, we get one LS+FT and one LS+4th every 50 GCDs. That’s 203.79 + 164.17 = 367.96 potency per pattern, giving us…
367.96 potency / 50 GCDs =
+7.36 potency per GCD, or
(367.96 potency / 50 GCDs) / 2.4 seconds per GCD =
+3.07 potency per second
Under the third and final approach, we end up with +203.79 potency across every 30 GCDs, for a benefit of…
203.79 potency / 30 GCDs =
+6.79 potency per GCD, or
(203.79 potency / 30 GCDs) / 2.4 seconds per GCD =
+2.83 potency per second
In the end, approach #1 (using LS as soon as possible with any FT or 4th hit) has the edge. It’s also a nicer approach in the sense that it frontloads Life Surge use, which could mean that you land an extra LS-buffed attack before an enemy jumps away or dies.
Conclusion: At a 2.4 second GCD, we should burn Life Surge on the soonest possible Full Thrust, Wheeling Thrust, or Fang and Claw (except during the opener).
HT - ID - Dis - CT -[Got LS? Use it!]- 4th - Phleb - TT - VT -[Got LS? Use it!]- FT -[Got LS? Use it!]- 4th
Note that this should work well at pretty much any reasonable level of Skill Speed. For this pattern to actually change, we would need a GCD length of about 2.5 seconds (in which case Life Surge always pairs perfectly with every other Full Thrust), or a GCD length of about 2.3 seconds (in which case there are 22 GCDs separating each Life Surge use).
Also, it's worth pointing out that the potency differences between these three approaches are incredibly small. If you're just more comfortable with Ye Olde Life Surge Full Thrust, then by all means, use that every time. But for a very slight DPS advantage, we'll want to follow my above advice.