IMO, where CB really shines is when you apply it to multiple enemies. Say a group of 3 enemies, then it hits for 300% + (3 * 150%) = 750% every 2 second for that group
Yes, that's why this skill is either take it with upgrade and use on stacked groups or just ignore it.
To get best result you need on that group cast it on few targets to multiple those dots, it's a kind of DoT stacking I would say, but in different manner.
Single Cool beats is "poor" mans firewall. Fire wall just gives 200% damage burn for everyone + fear. Pretty much the same result.
Which was why I disclaimed that I had not tested this... I was not sure it it ticked every 2 seconds for twice the damage.
This kind of inconsistency is also why I have a major gripe with DOT in this game. It should be ticking once per second for the listed damage (in this example, 300% damage), or once every two seconds for double the listed damage (again, 600% in this example). As you stated, some skills seem to do the latter, some don't.
I have not tested Toxic Cloud since it's "buff", but it seemed to me that the "buff" was not a "buff" at all, but merely correcting the numbers to what it actually did in game. At the time I made my Hunter video, Toxic Cloud claimed to deal 15% damage per second DOT and the upgrade, Contact Poison, claimed to deal a separate 25% damage per second DOT. However, with the Bow of the Griffon at 150+25 base damage, I was seeing two separate damage ticks every two seconds for about 175 damage (meaning it was 50% damage per second). Keep in mind I had about four total mage promotions from my Necromancer, and nothing more.
Walking Bomb was the same in this regard, except it would deal two ticks immediately, then one every two seconds for double the listed damage per second.
I'm just talking from my experience and basic math formula. If damage on DoT will be doubled I would feel it. Immolate damage is the same on direct and DoT part, some time ago I had even some post around it with Drasca, something with Immolate vs Fire mine on ele and numbers where there, definitively not 800% damage dot on immmolate. Cool beats for me is 500 damage and I can't see how it could lead to 600% ability.
It's not really rocket science I would say. Chain lightning with ring has 300% damage. It's 500+ ish damage, more when shocked what's obvious.
Poison damage on my alchemist is lame, around 200+ so it fits this 50% damage formula (which I agree with you wasn't a buff, just fixed tooltip).
As for the walking bomb.
It hits twice at start, yes it's true.
But this skill isn't just dot, it's direct damage + dot.
I think that in general tooltip is messed up on Walking bomb and direct damage is the same as DoT damage. It should be tested but from my observation for sure I know:
1) Both damage values at starts are pretty much the same.
2) You can crit with one of this values, so you get crit and normal damage at start. Probably those 2 ticks aren't really 2 ticks, but applying walking bomb explosion + dot. Explosion can crit.
3) If you look at explosions you can also see that other targets will be damaged at start twice, probably in the same way as first hit, but I'm not sure with crits on explosions.
4) DoT damage is every 2 seconds.