Most defenders are better than sticky notes, but their ability to be concrete should be very limited. Enemies should have a choice to attack non-defenders. It just shouldn't be an optimal choice. Otherwise the defender collects all the mobs and holds them with taunts, and we really do start playing Warcraft.
Agreed (although a challenging encounter can make it optimal to avoid the Defender).
Aegis of Shielding makes the Swordmage a much more appealing option by comparison. Have you even played a defender? Your comments seem uninformed. You can attack the Swordmage and deal full damage if you hit, or attack someone else, who probably has a comparable AC after the -2, and inflict severely reduced amount of damage if you manage to hit. Suddenly the swordmage looks like a much more appealing target. Personally, I try to get enemies to provoke my Aegis. I take as many teleports as possible to keep my marks as far away from me as I can. Because whatever I put my Aegis on will be contributing marginally, at best, so long as I can keep it off of me.
I don't actually see this (and yes, I played a Swordmage with an Aegis of Shielding in PBP). Compare a Swordmage to a Thief or Rogue. They both have Leather, they both have ability score, they both have magic, but the Swordmage is +3 AC whereas the Thief or Rogue is +0.
Attacking the Rogue is +1 to hit, +2 with a Charge.
Let's look at damage.
The Aegis drops damage by about 7 or 8 points at low level. I agree with you. This can be huge with regard to damage. It effectively negates most of the damage of a single foe. In a 6 round encounter, that can be 40 to 50 points of damage that it can negate or the equivalent of 3 heals if every single attack hits. It's has the potential to be huge.
But, there are still a few other things to consider. First, does the monster have an effect that's worth putting on a different foe? For example, weakness on a Striker. Damaging the striker doesn't matter as much as limiting the striker's effectiveness. Or, Dazing a Leader so that the leader has to choose whether to heal or to attack. There are situations where the damage portion of the attack isn't what's important, the rider effect is what is important. In fact, some rider powers actually do low damage to begin with because the effect is strong.
Second, how much damage does this actually negate? A same level monster with +5 to hit has a 30% chance to hit the first level Swordmage for 8.5 damage and 5% chance to do 12 damage (crit, D8+4). Or, it can get a 40% chance charging the first level Rogue for 1.5 damage and 5% chance to do 7 damage (crit). 3.15 average damage per round against the Swordmage, 0.95 average damage per round charging the Rogue. In reality, that saves 2.2 points of damage per round or 13.2 damage in a 6 round encounter if the Aegis can be used every single round.
In reality, it's just a bit stronger than a single healing power per encounter unless it is a long encounter if and only if the Aegis-ed foe decides to charge a PC other than the Swordmage every single round. But, the Aegis-ed foe is not necessarily forced to attack someone else. He could close blast the Swordmage and another PC or two. He could shift back and area blast the Swordmage and someone else. He could even charge bull rush a different defender to free up his allies where the negation of the Aegis is assumed by the monster (or charge bull rush a different PC into a hazard), so the monster does something else useful instead.
And, the damage reduction of an Aegis of Shielding doesn't necessarily occur every single round. It doesn't happen if the Swordmage doesn't have line of effect. It doesn't happen if the monster shifts and range attacks a PC more than 10 away from the Swordmage. It doesn't happen if the monster misses its target. And most importantly, it doesn't happen if a Swordmage uses a different Immediate Interrupt or Reaction power that round. Swordmage's have quite a few other Immediate Action powers that prevent an Aegis working in the same round (or alternatively, the Aegis prevents those other powers from working).
So yes, an Aegis of Shielding is a real nice power if one looks at damage mitigation only and one assumes that it can be used every round. But, it typically works out to be at most as useful as a single healing power (and as levels go up, this becomes less and less of an overall savings). Good. Not awesome.
But, a good DM can lessen the effects of powers like Aegis of Shielding just by using good monster tactics. The DM doesn't have to kowtow to the stickiness of the Swordmage.
I don't disagree that Swordmages can defend and can be effective. I just disagree that they are real sticky against multiple foes. Most of the time, that can be worked around.
Booming blade scales fairly nicely, actually. It's 1d6 + Con, so it scales with both attributes and magic weapon bonuses. Particularly at low levels, when you're most likely to use it regularly, it boosts a Swordmage's damage to Striker levels when provoked. Please feel free to walk away from my Booming Blade; you'll won't last long trying that.
If Booming Blade hits in the first place. If Booming Blade hits in the second place. If the target is still adjacent at the beginning of his turn. If the target doesn't have resistance or thunder resistance. If the target doesn't use a close burst or blast.
Yes, Booming Blade can do extra damage and often does. No doubt. But, it isn't hard stickiness and a DM can get around it. The adjacent clause is the easiest one to negate via other monsters (moving the Swordmage, or moving his BBed foe).
And like I said, if you run an atypical encounter then the encounter guidelines don't work too well. The example you gave was quite atypical, regardless of whether you think of it that way or not. You can claim that mistakes were made, but in my book a mistake is putting your Aegis on a Soldier. Not thinking to bring out a light source when suffering darkness penalties goes way beyond a mistake in my book. Seriously, what kind of N + 0 encounter lasts 12+ rounds at 6th level?
They did have a light source. The players just did not realize that a sunrod has a 20 radius and they could have lit up the entire room much earlier. That was their mistake. Being in the dark only gave the foes Combat Advantage. The hazard of the room was its length combined with the pits on the side that were hard to get around. The PCs also moved to the side of the room which allowed the pits to be more useful for the NPCs (a mistake in hindsight, but not one that could easily be determined ahead of time). It took quite a few rounds, even running, for the PCs to get within normal 10 square range for ranged attacks and even more for melee attacks. And because they were running, their own ranged attacks were at -5 to hit back. Plus, the enemies had move 6 (some PCs only had 5) and teleports, so they could teleport over the pits when they got in trouble. And, some of the enemy attacks had forced movement effects, so they could push the PCs away from them or into the pits.
You totally missed the point of the darkness / terrain effects combined with the abilities of the NPCs. That's why it was 12 rounds. The PCs had to run from one end of the room to the other, and then back again with some combat in the middle.
And yes, my encounters can last that long. This one did. The enemies moved back away from the PCs once the PCs got close and used the pits to segregate themselves away from the PCs.
Your analysis of this encounter combined with your analysis of Defenders and Wizards here makes me realize that your DMs are probably not challenging you as much as they could if you consider this an atypical encounter (especially considering your comment about your games typically having moderate to large size areas). 4E is actually a pretty easy game once the PCs get a bit above low level if the DM doesn't pull out the stops (and that doesn't mean higher level encounters, it means encounters that challenge the normal tactics of the PCs like this one did).
A long room like this, even without darkness, could allow Artillery to light up a Wizard at the other end. I'm not quite seeing how it's tough to target a Wizard in many encounters unless it's a small room where the Defender can partially hinder some foes and even that can be worked around.
You have to play it like a wizard in order to excel.
No doubt. They're still wimps except for their Dailes.