Looks solid for Dark/Elec. I find I only need to slot IOs once and they provide better bonusses than SOs - but others prefer SOs. Also Elec only really shines when you've got a second source of electrical damage - otherwise you aren't going to be flattening your target's end (and end drain on mobs is pretty much all or nothing) and doesn't contain a high damage single target attack, making it weak unless backed up with more electricity.
In short, if for thematic reasons you want a Dark/Electrical defender using SOs that's not a bad way of doing it. But /Electric is IMO a bad plan. If you want to solo and prevent the foes hitting back, your best bet is probably /Ice (/Psi isn't bad either) whereas for AoE foe can't hit back goodness, your best is probably /dark (and stack the tohit debuffs).
Hi there. It looks like a solid build for Dark/Elec to me too. The only advice I would give is consider dropping Aim for Petrifying Gaze earlier on in the build. Two Mag3 holds means you can keep a couple of Lietenants out of the battle or stack them on a Boss.
Also, you will be team reliant with Dark/Elec. I got mine into the 30s and it is possible to solo, especially when you have Fluffy and Sparky working together but it can be slow going. Good luck. 
@Dante EU - Union Roleplayer and Altisis Victim
The Militia: Union RP Supergroup - www.themilitia.org.uk
Well It's kindo thematic the elec thing... Always wanted to see what it would be like to have two pets as a defender, so that won't change. 
Anyways, I'll see what I can do about that second hold.
Thanks
Hey, I'd like some thoughts on this PvE build please.
Hero Plan by Mids' Hero Designer 1,401
http://www.cohplanner.com/
[u]Click this DataLink to open the build![u]
The Liaison: Level 50 Magic Defender
Primary Power Set: Dark Miasma
Secondary Power Set: Electrical Blast
Power Pool: Flight
Power Pool: Fitness
Ancillary Pool: Electricity Mastery
Hero Profile:
Level 1: Twilight Grasp -- Acc(A), Acc(5), Heal(7), Heal(13), Heal(19)
Level 1: Charged Bolts -- Acc(A), Acc(3), Dmg(15), Dmg(34), Dmg(46)
Level 2: Lightning Bolt -- Acc(A), Acc(3), Dmg(15), Dmg(34), Dmg(46)
Level 4: Tar Patch -- RechRdx(A), RechRdx(5), RechRdx(11)
Level 6: Darkest Night -- EndRdx(A), EndRdx(7), ToHitDeb(9), ToHitDeb(19), ToHitDeb(23)
Level 8: Ball Lightning -- Acc(A), Acc(9), Dmg(17), Dmg(34), Dmg(48)
Level 10: Shadow Fall -- EndRdx(A), EndRdx(11), ResDam(13), ResDam(17), ResDam(23)
Level 12: Hover -- EndRdx(A)
Level 14: Fly -- Flight(A)
Level 16: Swift -- Flight(A)
Level 18: Health -- Heal(A)
Level 20: Stamina -- EndMod(A), EndMod(21), EndMod(21)
Level 22: Howling Twilight -- RechRdx(A)
Level 24: Fearsome Stare -- Acc(A), Acc(25), Fear(25), Fear(37), Fear(43)
Level 26: Short Circuit -- Acc(A), Acc(27), EndMod(27), EndMod(31), EndMod(37)
Level 28: Tesla Cage -- Acc(A), Acc(29), Hold(29), Hold(37), Hold(43)
Level 30: Aim -- RechRdx(A), RechRdx(31), RechRdx(31)
Level 32: Dark Servant -- Acc(A), ToHitDeb(33), ToHitDeb(33), ToHitDeb(33), Heal(40), Hold(40)
Level 35: Voltaic Sentinel -- Acc(A), Dmg(36), Dmg(36), Dmg(36)
Level 38: Thunderous Blast -- Acc(A), Acc(39), Dmg(39), Dmg(39), Dmg(40)
Level 41: Thunder Strike -- Acc(A), Acc(42), Dmg(42), Dmg(42), Dmg(43)
Level 44: Charged Armor -- EndRdx(A), EndRdx(45), ResDam(45), ResDam(45), ResDam(46)
Level 47: Power Sink -- RechRdx(A), RechRdx(48), RechRdx(48)
Level 49: Petrifying Gaze -- Acc(A), Acc(50), Hold(50), Hold(50)
------------
Level 1: Brawl -- Empty(A)
Level 1: Sprint -- Empty(A)
Level 2: Rest -- Empty(A)
Level 1: Vigilance
Thanks