I just have a generally negative view of ranged attacks for defenders. I can see where its handy, but the trouble is that it competes against Booming Blade (HBO-capable, helps make you sticky, which is something non-Fighter defenders have trouble with) and Sword Burst. I think its better than Greenflame Blade and if I was a Human, it would be the 3rd at-will, and I guess its also good before you get Solid Sound in the Paragon tier.
None of the swordmage At-Wills other than Greenflame Blade matter much for HBO, because Swordburst can't be used with HBO, Lightning Lure if Ranged, and Booming Blade and Frigid Blade both require that the foe starts their next turn next to you, which is somewhat unlikely. Also, your mark effect goes off at range man, you're perfectly sticky from 10 squares out. Oh, and the ability to attack skirmishers/controllers/lurkers/artillery against their weak defense is great.
Shielding Swordmages should probably take Booming Blade and Lightning Lure to start out. If you get arcane reach switch Lightning Lure to Swordburst. If your ConMod gets up to +6 or +7, consider getting Frigid Blade instead of Booming Blade.
Assault Swordmages should probably get Greenflame Blade and then either Booming Blade or Lightning Lure, depending on how often you face Fort weak foes.
Booming Blade can be quite good on an OA, simply move next to them when it comes to your turn and it's the same situation as if you'd hit them normally. It's just a round delay as worded.
Lightning Lure is often pointless; if there's someone next to you then you don't want to use it, but if there isn't, why aren't you moving next to them instead? I think Lightning Lure would be of more use if you were not really tanking, but that would likely require at least one other Defender and at least one other melee-heavy beyond that taking a good bit of the heat, and still seems... inefficient, as you're now a Striker with health that doesn't do very good striking. Lightning Lure pulls them towards you, which is often counter-productive in any build that can use it effectively the first time (wants to
not be near enemies and use ranged attacks.) It seems like it could be very useful in certain situations, but not often enough to even necessarily warrant being used every encounter as an encounter power. Booming Blade/Frigid Blade makes you very sticky and Sword Burst makes you painful and a good minion sweeper.
Sword Burst is amazing. It's the same reason that the Ranger is so good, multiple attacks are awesome for damage. Simply getting two enemies in that burst with ~18 Int and a +1 magic weapon will be much better than any damage a single target attack will give you. 1 attack, 2[W]+stuff, [W] = 1d8, 2d8+4+1 = 14 average. 2 attacks, 1d6+stuff each, 2d6+2*stuff = 7+10 = 17 average. This only gets worse as your modifier becomes higher, and and becomes the dominating factor in your damage. Level 30, ~28 Int with +6 weapon and WF, 6[W] attack = 6d8+stuff = 27+9+6+3 = 45, 2 attacks = 2*(2d6+stuff) = 4d6+2*18 = 50. With only
2 targeted. Without things any other bonuses to damage factoring in. 3 attacks does about as much on average as a single 12[W] attack... Every additional creature you target adds 1 to the multiplier of your damage. Multi-targeting is very good for Defenders, because it's unusual and outside of their role. Something important to note is that the damage is spread throughout multiple targets, which is not as valuable, but the dampening effect of this is not as dramatic as the ridiculousness of this. You're not giving up half your damage against each target to do this, you're giving up 1 or 2 damage.
Besides that, it averages the same as a minion clearer vs. Greenflame Blade. Greenflame Blade needs the first attack to hit to hurt everything else for Str mod damage. Sword Burst makes a separate attack. Greenflame Blade will be more swingy, hitting everything when it hits, but missing everything when it misses. Sword Burst will have a separate attack vs. everything, and be much more likely to hit some and miss some. Greenflame Blade's extra damage is likely to be complete craptastic against anything besides a minion, Sword Burst's is not (since it's all the same damage, and likely only 1 or 2 less than the
primary of Greenflame Blade.) Greenflame Blade effectively hits in a burst 1 centered on your target, which is most likely going to be a close burst 1 offset by 1, which will hit behind the target but miss behind you (relative to the target.) Sword Burst will hit all around you. I find it much more likely that you'd miss targets when not hitting behind you than you'd miss targets when not hitting behind your target (not adjacent to you so probably ranged, but really close to the party's melee for some reason..) If you only have one target, Greenflame Blade is likely better, but if you only have one target, why aren't you using Booming Blade?
In conclusion: I don't think Lightning Lure is likely to ever be that useful, as it both provokes and pulls enemies closer (seemingly both only useful in one build at a time, at least as an at-will) and
I don't see why even Assault Swordmages would take Greenflame Blade unless they were planning on using it with HBO a lot,
and for some reason didn't like Arcane Reached Sword Bursting, as Sword Burst is almost strictly better. It (with more than one target, which is assumed for either power) does much less damage, (so much so that it's mostly on useful on minions, which are likely to be easier to hit and therefore easier to kill on average with a separate attack targeting them) is swingier, (which is generally only considered beneficial to the underdog) hits a less useful area, (arguable, but I definitely think so) has a much better benefit from feat, (also arguable, but I also definitely think so) and, though roughly equivalent on average, attacks a defense, giving more ability to tailor your attacks to weaknesses in enemy defenses (you've got enough AC targeting things, like say your melee basic attack...)
