Someone needs to put up a guide for FotH Fissure because it's definitely not easy to use optimally. I think I spent like 5 minutes killing a rift boss that's one of those Act4 meteor summoning teleporting bastards meaning FotH will never hit for full damage. Judgment doesn't hold him in place either. That was terrible.
Some casual observations:
1. You can put FotH on one edge of your screen and another on another edge and they will still link. However the casting range is a little bit less than that so you will have to move slightly to put one on the other end. You basically can damage the whole screen in one line but the link (arc) is only 185% weapon damage so it's good for trash mobs but not that useful for elites.
2. To optimize damage for a single mob, you want to place two FotH touching the mob but not on top of it, making a line with the mob in the middle, so it'll take the localized lightning damage from the two FotH yet still getting the arc damage from the link.
3. The slow attack speed while two-handing is actually quite terrible for FotH fissure. Because one only stays up for 5 seconds, assuming you only have 1 aps, you'll lose 1 second before you can cast the other one to generate an arc. If you're surrounded by mobs, sometimes you may not even get to cast FotH where you want it to be so when the second one comes up, the first one is already almost over. One of my main problems with the skill.
4. It doesn't seem possible to create a triangle arc with FotH. If you cast two in a line, then another one on another axis between them, the original arc will break while the two previous ones will just arc with the new one. So it seems like a line is the best you can do for arc'ing and casting more than two doesn't seem to do much in a small area.
5. Following 4, unless you can generate wrath really fast, you won't get to do more than 3 optimally because by the time you generate the wrath to cast the fourth one, the original ones area dead. So I would suggest just casting two at a time, letting them die off, then cast another two.
6. This skill is terrible for fast moving/teleporting mobs. It's so bad. Spending 3 seconds to do Judgment -> FotH -> FotH works sometimes but it's not sufficient.