Just from looking at a bunch of other threads it just seems some people love them and some don’t.
The thread on Flickr was very useful but information on Helios for example still seems to be sketch. Does it do huge damage at lvl.5? Is it just worth it with 1 point?
What do you guys reckon
For a breakdown of all the skills, this is the best place to start:
Helios is ok in NVHM. In fact, I did a siren run through pretty much only going up the Cataclysm tree (so Helios, Backdraft, Blight Phoenix, Cloud Kill - the works). It was a lot of fun but, by the end, it gets really hard to figure out which skill is doing what!
The problem comes when you get in to UVHM and your skill build really starts to matter more - some things scale well into UVHM and OP levels, others simply don’t. And that’s what the various guides (like the one I linked above) reflect.
The short answer would be, do whatever you like through NVHM and have a blast, never be afraid to respec if something isn’t working for you, and review your build before heading in to the next mode.
Helios can do some damage if you also have specced into Subsequence, so that Helios is firing off multiple times in one Phaselock sequence. Especially if you’ve also taken Ruin so the targets are slagged (after the first one mind you, as Helios procs before Ruin.)
Blight Phoenix has some interesting effects, though I rarely spec into it anymore. It can stagger melee attackers that come into its area of effect, and it can also break up things like rocks tossed by bullymongs (in short it affects just about anything that’s can take damage, living enemy or not, famously including barrels but also skag piles and such.) It’s not 100% reliable for those cases though. It can be useful for some extra healing if you’ve got Life Tap going or a Moxxi weapon in hand. (It’s amusing to hear Life Tap go off when you pass by one of those inexplicably damageable Hyperion containers when Blight Phoenix is up (funny to watch Scorn zap those containers too)).
There are apparently tricksy ways to abuse Backdraft with a certain build but I’ve never played with it. I usually don’t spec into it.
Backdraft build
Never tried it and haven’t seen any talk of it at OP10, so idk
Some people take helios over flicker to move down the tree
Aside from the above Backdraft build (which is stupendous btw), Backdraft has two marginal uses :
Helios : as stated, good in the OP levels at 10/5 , good sub-OP at 5/5 - but it really only works well with SubSequence. On the downside it makes a big visual mess which I don’t like. If I’m going for critical hits, I won’t take it since it obscures their heads.
Blight Phoenix : not much to add. I always take one point for Life Tap and for its reflective ability. Any more than that and it will pop barrels.
What’s relevant is you have quite a few spare points to drop in the tree to get to Ruin. So a point in Backdraft and BP is not wasted. A single point in Flicker for the Siren COM? Definitely! Any more? Only if you have nowhere else to put them.
Depends on your preference.
To go down chain reaction and cloud kill. You need to pick either flicker, immolate and helios. If you want more elemental chance go flicker, if you go into ffyl more pick immolate, if you need other elemental effects on your phaselock get helios (although it might pollute your screen if you are gunning for crits). The 3 aren’t game changer (except for immolate on raid boss).
Now to go down Ruin, you need 5 points to spend to those 3 skills plus Backdraft and Blight Phoenix. Again they are not game changers so pick what you like.
My preference varies depending on the enemy/map i am facing; whether i am solo or not; or raiding or mobbing. But most of the time I get Helios at 5/5 and 1 point for Flicker and Immolate (for com consideration); and Blight Phoenix and Backdraft for reasons stated by Boss Jefe above.
Just for giggles I specced 5/5 in both Backdraft and BP. BP will actually melt and kill stuff that’s slagged if you let it. I did a tubby hunting run in the Dust and the bitty lil spiderlings definitely didn’t last long, even unslagged. I got into the habit of throwing out a Scorn when a bunch of spiderants started to close in on me so they would be slagged and ready for my pyrocaustic wings. Normal, non-elementally-charged spiderants that weren’t gallants or monarchs melted noticeably too.
The Backdraft nova is a nifty thing to have on deck for the reasons posted earlier up above, but the added fire melee damage doesn’t make too much of an extra mark besides, well, when punching bitty lil spiderlings. 
Anyway, it was fun to play around with these two skills I don’t use much. I’m probably gonna keep BP, it was cruelly amusing to watch those poor spiderants stumble around me, yelping as they melted.
Yeah this is why I went with 5 points for BP after the cap increase. It gives me access to ruin and kills little annoying enemies like midgets, spiderlings, skag pups, pretty much anything that’s a bitch to hit with the accuracy penalty from my cat com.
Not to mention the wings just look great in co-op