Did some more testing on WW/Rend. I’ll just give my results first, so people who are only interested in that can get the quick takeaway.
Results:
- Hard cast rend and Ambo rend cannot stack separately, i.e., you can’t have 2 stacks of hard-cast (HC) Rend and 2 of Ambo-rend.
- Ambo-Rend seems to overwrite hard-cast Rend, i.e. if you’re fighting in density, throwing in occasional HC Rends to proc AD is not going to help you. If you want to get significant AD out of Rend, you have to sit there manually spamming it for several seconds (not more than 3, since then Wastes 4 will drop, cutting your damage to 1/3).
- I am not sure if HC rend overwrites Ambo-Rend, will have to test more later. (Edit: it does overwrite)
Method
To test whether Ambo-Rend and HC Rend can stack side-by-side, I ran trials on damaging enemies using two procedures. In procedure 1, I just used WW to apply Rend, and in procedure 2, I pretty much continuously HC Rend, tapping WW every half second or so to apply Ambo-Rend. I nerfed my damage, so as not to kill my target too quickly, by removing all damage passives and legendary gems, and using 2 BK weapons with the damage range rolled off and no sockets.
I did 3 sets of trials, on Manglemaw, Rakanoth, and Ghom. For Rakanoth and Ghom, who are bosses that spawn with the same amount of health each time, I timed taking their health from 100% to 0%. Manglemaw’s health is variable each time he spawns, so I timed 100% to 50% health, and then 50% to 0%, on the same instance.
Manglemaw, procedure 1: 27 seconds
Manglemaw, procedure 2: 27 seconds
Rakanoth, procedure 1: 2 minutes, 58 seconds
Rakanoth, procedure 2: 3 minutes, 0 seconds
Ghom, procedure 1: 4 minutes, 3 seconds
Ghom, procedure 2: 4 minutes, 17 seconds
If Ambo-rend and HC Rend could each stack separately, you’d expect mixing the two together to produce significantly more damage. It sure doesn’t look like that’s happening.
To test whether Ambo-rend can overwrite HC Rend, I headed to the tomb of the skeleton king, where I spawned the four towers that summon skeletons. After killing all the surrounding enemies and 3 of the towers, I again nerfed my damage, and applied HC Rend to the tower. As expected, this procced AD on the couple of surrounding skeletons. Then I applied Ambo-Rend to the tower. As expected, this did not proc AD onto the skeletons.
Then I applied HC Rend to the tower, immediately followed by Ambo-Rend, and didn’t see any AD procs hitting the skeletons. I repeated this 20-25 times, and saw 0 AD procs after I’d applied Ambo-Rend. So it looks like Ambo-Rend is overwriting HC Rend.
Like I said, I’m not sure if it goes the other way: whether HC Rend can overwrite Ambo-Rend. I may test that later, or if somebody else feels like doing it, knock yourself out. (Edit: a few days later I re-tested, and HC Rend does seem to overwrite Ambo-Rend, as well.)