Short answer - YES, it does.
I’ve tested how does Tempest Rush (TR) works with Mythic Rhythm (MR) and how is it interacts with “new” Won Khim Lau (WKL)'s mechanic which auto-cast Cyclone Strike (CS) and how is it interacts with force pushing of Sweeping Wind (SW). Here is the answers:
- TR grub (snipe, idk the right word) MR effect for the full duration and the final explosion of the ice rune as well and this damage effect is multiplicative
- WKL’s auto-cast of CS does not break sniped by TR effect of MR
- force pushing of SW while channeling TR (for extending the duration in long empty passages e.g.) does not break sniped by TR effect of MR
The effectiveness of MR + generator combination is lesser than 1.4 multiplier.
Indirectly it comes from Convention Of Elements (COE) and TR mechanics, due to this combination commonly uses in high GRs COE TR builds.
The mechanic is:
- you have 5 elements in infinite loop iteration.
- each element persists 4 seconds (full loop duration - 20 seconds, every 20 seconds you will see the same element).
- TR Flurry rune get 5 stacks every second, the maximum of 100 stacks every 20 seconds (1 stack every 12 frames (of 60 frames in 1 second)).
- Commonly for that build attack speed goes from paragon 10%, dual wielding 15% and Seize The Initiative (STI) 30%. You get 2.17 Attacks Per Second (APS) with STI or 1.75 APS without. You lose time doing 3 generator attacks. Corresponding to d3planner site that time differs from reverse value of your APS multiplied by 3, so it’s not 3 * 1.75**-1 == 1.71 seconds (103 frames), it takes less time.
Corresponding to the mentioned above site it takes:
from 62 to 78 frames with or without STI, corresponding for Fist of Thunder (this is the fastest generator),
from 63-65 to 77-80 frames with or without STI, corresponding for Way of the Hundred Fists: Blazing Fists (numbers vary because of crits).
- You lose from 6 to 7 stacks of TR Flurry because of auto-attack. It’s from 6% to 7% damage loss.
- Finally you get from 30.2% to 31.6% damage increase, multiplicative depends of STI works or not, respectively, instead of 40%.
Other Monk’s passive damage boosters:
- STI gives you from 0% to 24% damage increase, multiplicative (2.17/1.75*100 - 100).
- Relentless Assault gives you always exactly 20% damage bonus, multiplicative.
- Other Monk’s passives give you only additive bonuses and even if tool-tip says 20% damage increase - IRL it’s lesser (additive to Teaguk which could give you up to 80% at maximum Gem level and Blinding Flash: Faith in the Light with 29%. So regular 20% damage passive would give you in that case about 9.5% damage, multiplicative.
- Beacon of Ytar gives you around 5-9% multiplicative damage because of Crimson 's set and exact value depends of your Cool Down Reduction (CDR). More CDR you have on gear less damage you get from the passive (e.g. with CDR bonuses only from paragon, Crimson’s set, shoulders and one of your rings you get about 8% damage increase, multiplicative).
Mythic Rhythm is the most effective monk’s damage passive for TR build, gives you from 30.2% to 31.6% damage increase, multiplicative. Depends of monster’s health lost, but most of time gives you the maximum bonus.
Seize The Initiative is the second effective monk’s damage passive for TR build, gives you from 0% to 24% damage increase, multiplicative. Depends of monster’s health lost, but most of time gives you the maximum bonus.
Relentless Assault is the third effective monk’s damage passive for TR build, gives you always exactly 20% damage bonus, multiplicative.
Other Monk’s passives give you less than 10% damage, multiplicative.
Mythic Rhythm is the best passive for damage, however this passive required additional active slot for generator, so it’s not that good how it could seem from the first sight. There is no free 40%, multiplicative. There is only about 30% damage, multiplicative at cost of 2 slots.
With Attack Speed increase bonus on weapons and hands for example you not only increase your TR damage by certain value, but also you increase the number of possible stacks of Flurry and increase your damage that way in addition.
For Tempest Rush builds:
Mythic Rhythm > Seize The Initiative > Relentless Assault