Welcome to a road less travelled. It is perhaps not as rarely travelled as some, but it is far from common. In what follows I will outline some of what I have down with Radiation/Electrical, but do not take it as a statement of what you should do or that it is the only thing that can be done. My sole purpose here is to illuminate what has largely lain in darkness. So let's get down to business, shall we?
What, in broad terms, is a Radiation/Electrical Defender?
The build is, like its other Radiation primary siblings, a very decent solo platform (if that is what you want to do) that also supports groups it finds itself in very nicely. And like its siblings, it is not a way to make a super-blaster that has defenses and can heal.
Wouldn't I be better off choosing Dark or Radiation Blast for secondary powers?
Better off? Depends on precisely what you want to do as a Radiation Defender. Whatever you choose, a secondary powerset is an offensive tool and so they all share in common means of dealing damage. The thing is that the tools are different. Frankly, Electrical Blasts seems in a lot of ways more designed for Defenders to use than Blasters.
So what does Electrical Blast bring to the table?
The Electrical Blast set combines a number of elements that as a whole can't be found elsewhere--Aim, a pet, a hold, radial area attacks, and endurance drain.
I heard that Endurance Drain is a very weak secondary effect.
Endurance draining is both a source of weakness and strength for the set. Frankly you probably will not see a lot of benefit from the secondary effect until your mid-20s when there are a lot of foes that make use of special attacks, and even then unless you have Short Circuit they will get to use most of those attacks on you with the best you can hope for is to weather the storm and then continually deny them the opportunity to recharge themselves. But if you do take Short Circuit and slot it up some, it becomes a very powerful took for denying many dangerous foes attacks you would really rather didn't take effect on you and your comrades.
Well I heard the pet (Voltaic Sentinel) sucks.
Keep in mind where you most likely heard that from--a Blaster. While we share some powersets with them, a Defender is not a Blaster with weaker damage. It is true we do not deal the same damage as a Blaster in a shot, but there is a lot more difference between our ATs. Their secondary powersets and our primaries don't overlap to a great extent, and those powersets heavily influence what either can do and hence what is useful and to what degree. Blasters typically naysay Voltaic Sentinel because they can kill everything in a spawn in short order. As noted, we don't deal the same magnitude of damage, so VS is less likely to be left over sitting there with nothing to do and no ability to move. Consider also that unlike Blasters, you can debuff what you're fighting's defense and resistance to damage--your Voltaic Sentinel will hit more often and for more damage. Since Blasters transition from "can handle this without VS" to "don't attempt this alone" very quickly, VS brings little to the table to them. But with our debuffs, we have a much more gradual transition from "don't need VS" to "VS can help me", to "I'm not touching that".
Okay, supposing I'm interested, what are the important powers to take?
The Radiation side of things has been expertly covered by SoulHealer
here, so I'll just deal with the highlights quickly:
Radiation Infection - Being offensive or being protective, this is a pivotal, go out and get it now, you should have started with this, make sure you slot it up power. It simply is that good. For a very low endurance cost it makes those affected have a harder time hitting you while making those same things easily hit by everyone else. While plenty powerful with no slots given to it, it really shines when fed a diet of To-Hit Debuff and Defense Debuff enhancers.
Acclerate Metabolsim - The second piece in the Radiation Defender Triple Crown, AM is hands down one of the best buffs in the game, and again serves both the protective and offensively built Rad Defender well. You will want to slot this heavily with Recycle Reduction enhancers.
Enervating Field - The final piece of the Big Three, this takes your damage upward considerably. You're not a Blaster, but with this baby you can still be a respectable damage dealer. However it is an endurance hog. You will want to do some work on the cost of this.
Lingering Radiation - While not as obvious as the aforementioned powers, this power is a serious utility, slowing both the affected foes movement and attack rate. Its only weakness is to be found in the same powerset as the above powers. It is both fast casting and not a toggle. Why then not speak of "the Big Four"? The above powers are either automatic hit or impact you and your allies. This power requires a to-hit check and so best piggyback's on application of Radiation Infection.
EM Pulse - Its been called an "Oh S##t!" power, but I like to think of it as a, "Okay, I'm sick of this!" power. This one swings battles around as what was beating on you and your friends decides that standing around in a daze, unable to act for a long period while you and yours deliver punishment.
Of the remaining powers please refer to the link above. As to Electrical Powers. . .
Charged Bolts - This power is manditorily possessed as all initial secondary powers are. It is your fastest recycling damage dealing power. While I have not confirmed this, it appears that as typically slotted (1 Accuracy, 5 Damage) that it should hit for about 80% of what Lightning Bolt does based upon what I observe from my slotting (see my sig below).
Lightning Bolt - A very solid and worthwhile attack. Again somewhat bread and butter. It hits for about half the value of Zapp similarly slotted for damage in my experience.
Ball Lightning - This is the basic AE attack for the powerset. Its great advantage over the area attacks you find in other blast lines is that it doesn't require any great effort to maximize the number of targets you hit. Just aim for the center and everything within range of that target gets hit.
Short Circuit - Remember how I noted above that we aren't Blasters? Well one of the things Blasters hate about this power is no great concern to us--that it is a point blank, area attack. Radiation Infection (and Lingering Radiation in combination) work well to keep us from being hit often, so manuevering into the middle of melee and letting loose is no great shakes for us. Appropriate slotting can allow this power to yank all the endurance from all but the highest con targets nearby. It can also be slotted for damage, though if you do so to any great extent you'll find that you need more than one use to empty nearby foes of endurance (guess its a good thing you have Radiation Infection and can often afford to stand around and wait for Short Circuit to recycle). It is a real joy to use Short Circuit on a bunch of Freakshow just before delivering the killing blow with Ball Lightning as if they are out of endurance they can't use their last second heal power.
Aim - People invariably think of this power in too limited a fashion, usually focusing on it allowing blasts to hit. They then conclude "I'm not planning on using my blasts and so I don't need it", or "I have Radiation Infection and so I don't need the help in landing powers". Aim both adds to damage and to accuracy and does so regardless of the power dealing damage or not. So even if you're going to hit anyway with a damaging power, you'll hit for more. And if the power doesn't deal damage you're still more likely to hit. For powers that when you use them you really don't want a miss--say EM Pulse or Thunderous Blast--Aim is your ticket (with Thunderous Blast gaining from the increased damage too).
Zapp - This is your snipe attack. Did I mention that Radiation Infection makes you harder to hit? Well if you're hard to hit, you can be standing on the target and not have a problem with sniping him, as is shown
here. It is definitely a power worth picking up and slotting.
Tesla Cage - Dark Blast may offer better crowd control via Tenebrous Tentacles, but no other secondary line offers an as readily usable Hold. Single target, but that single target can't move or take actions and its toggle powers shut off. With appropriate slotting or making use of perma-Hasten (and perma-Accelerate Metbolism) the recycle time is short enough that you can yank two or more things out of combat and keep them out.
Voltaic Sentinel - Already commented on above, this power is quite useful to the solo player as your other debuffs allow it to hit well and hit hard. I'm currently estimating that at full slotting it will hit, with Enervating Field in effect, for 150 damage against even cons. 1500 damage for 37 endurance. . .how can you say no?
Thunderous Blast - I've only recently taken this power, but from what I've seen I'm in love. Completely unslotted for damage it dealt 50 smashing and 110 energy damage to the horde of even cons I used it on--that being without making use of Aim or Enervating Field. It also drained all or all but the tiniest sliver from the things I tested it on. As it drains all of your endurance when you use the power, be sure to use as much of that endurance as you can beforehand. Toss out a Voltaic Sentinel to deal with things that live through it, pop Aim before you use it and toss a Ball Lightning as well.
Looking at the Power Pool powers, there are two that really stand out to my mind, with all others being a matter of taste and fulfilling specific functions. Those two powers are Hasten and Stamina.
Hasten - There are builds that really don't need Hasten, and this is one of them. You can get by perfectly well without Hasten. But Hasten can also be used to good effect. It synergizes with Accelerate Metabolism quite well, with both increasing recycle rates on powers and Accelerate Metabolism providing the extra endurance you'll be working your way through with Hasten.
Stamina - Accelerate Metabolism is a beautiful thing, but by itself it won't keep you supplied. While there are specific AT builds that do not need Stamina, you are heavily advised to take it with this one.
Any tactical hints on pulling this all together?
Working with a group and working solo start off similar. Lead with Radiation Infection. Because of its relatively long activation time the best time to use the power is before things are mad at you and you can afford the time. As it reduces accuracy you'll also tend to live through the return volley you'll get from making a bunch of mobs mad with the power. I generally follow this up with Lingering Radiation as you might as slow down how quickly they can make attempts to get past Radiation Infection and hit you. In a group you'll likely apply Enervating Field and then get to work blasting, healing, or doing whatever the situation calls for. Solo I then run to my anchor (yes. . .I run to the angry mobs) and once there apply Enervating Field. The reason for this is the mobs are mad at me and being in their midst keeps them clumped together. Hmmm. . .with Ball Lightning, damage slotted Short Circuit, and Aim what ever could I be doing standing in the middle of a group of mobs that have a hard time hitting me?
Anyway, hope this sheds some light on the path of the Rad/Electrical.
