I also have a solution for
FROST DKs for soloing Yogg 25 No Lights 'cus many have asked me how I do it as Frost DK and they say it's impossible, yada yada yada....
Anyway,
1st Phase: Kill 8 Big Guys near Sara so she evolves into Yogg-Saron, wait for a 9th to spawn before you kill her and then bring the 9th Big Guy out.
Put the big guy to 50% with Frost Fever (+ Blood Plague) and when tentacle grips you then Howling Blast the big guy who is near you which will instantly kill the gripping tentacle.
After that, run over to the huge tentacle with over 1M+ HP, Put diseases on it and auto attack a little bit, be SURE to stand near it so you can Howling Blast when a gripping tentacle comes, rinse and repeat until portals spawn.
2nd Phase: Go into portals, this is pretty much straight forward. Kill the mobs blocking the brain room and enter the brain room and kill the brain till it automactilly kicks you out. (That's around 2M hp of the brain.)
3rd Phase: Once you're out, do NOT start dpsing on Yogg-Saron, it's no point. I tried it and it didn't work at all since the flow of adds would just continue to slaughter me.
When you get out, wait to round up a big amount of adds, pop Army of the Dead so they can taunt of the adds of you.
Now you should have plenty of time to kill Yogg-Saron in and you should get your kill!
I used talents:
T1: Rotting Blood (Blood Boil to spread disease from big tentacle to gripping one.)
T2: Lichborne (Great for Fear effects etc. + your Death Coils will heal you for a quite big amount.)
T3: Death's Advance (combine with Unholy Presence as macro to run faster.)
T4: Death Pact (straight up heals 50% of your HP)
T5: Blood Tap (This is great if you saved up a lot of RP and spended it then you will get a lot of charges and it's also good to save imo.)
T6: Desecrated Ground (Great for cc breaking from yogg-saron etc.,)
You can also use "Gorefiend's Grasp" since you can pull all the mobs to your Army in 3rd Phase.
If you have any more questions or this confuses you, tell me!
EDIT: I almost forgot! You should Blood Boil the gripping tentacles aswell for extra dmg and spreading diseases!