Separate reschedule and extend

sim/core/dot.go

@@ -111,11 +111,8 @@ func (dot *Dot) Rollover(sim *Simulation) {
 	sim.AddPendingAction(dot.tickAction)
 }
 
-func (dot *Dot) RescheduleNextTickAndExtend(sim *Simulation, numTicks int32) {
-	dot.NumberOfTicks += numTicks
-	// Set duration to remaining ticks, minus the elapsed time since last tick
-	dot.Aura.Duration = time.Duration(dot.MaxTicksRemaining())*dot.tickPeriod - sim.CurrentTime + dot.lastTickTime
-	dot.Aura.Refresh(sim) // update aura's duration
+func (dot *Dot) RescheduleNextTick(sim *Simulation) {
+	dot.RecomputeAuraDuration()
 
 	dot.tickAction.Cancel(sim) // remove old PA ticker
 

sim/shaman/items_wotlk.go

@@ -61,13 +61,19 @@ var ItemSetFrostWitchRegalia = core.NewItemSet(core.ItemSet{
 				OnCastComplete: func(aura *core.Aura, sim *core.Simulation, spell *core.Spell) {
 					fsDot := shaman.FlameShock.Dot(shaman.CurrentTarget)
 					if spell == shaman.LavaBurst && fsDot.IsActive() { // Doesn't have to hit from tooltip
+						// 4p t10 immediately updates the tickPeriod based on current haste
+						fsDot.RescheduleNextTick(sim)
+
 						// Find the number of ticks whose duration is closest to 6s.
 						// "our testing confirms that the 4pc t10 setbonus adds to FS the closest number of ticks to 6 seconds always"
 						// https://web.archive.org/web/20100808192139/http://elitistjerks.com/f79/t76510-elemental_patch_3_3_now_more_fire_nova/p25/
-						fsDot.RecomputeAuraDuration()
 						tickPeriod := fsDot.TickPeriod()
 						numTicks := int32(math.Round(float64(time.Second) * 6 / float64(tickPeriod)))
-						fsDot.RescheduleNextTickAndExtend(sim, numTicks)
+						fsDot.NumberOfTicks += numTicks
+
+						// Set duration to remaining ticks, minus the elapsed time since last tick
+						fsDot.Aura.Duration = time.Duration(fsDot.MaxTicksRemaining())*tickPeriod - (tickPeriod - (fsDot.NextTickAt() - sim.CurrentTime))
+						fsDot.Aura.Refresh(sim) // update aura's duration
 					}
 				},
 			})