Ill/radiation advice

Most of what you would ever want to know about your Illusion/Radiation Controller is in the guide, linked in my sig. There is a section where APP power choices are discussed.

Frankly, there are good reasons for each of the APP sets. I recommend taking a set with a fast single-target blast, to make a nice attack chain with Blind-Spectral Wounds-Blast-Spectral Wounds. (That would leave out Earth. While there are some nice things about the Earth APP, you don't really need the heal, as you have one. You don't really need the melee attack and the short-range AoE, as you will be safer staying at range.)

Many people love the Psi APP for the mez protection in Indomidible Will. I find that my Ill/Rad doesn't have much of a problem with getting mezzed. Also, there are a number of foes in the later part of the game who are resistant to Psi attacks, and most of the damage from Illusion is Psi. Using a different damage type can make dealing with Robots and other Psi-resistant foes easier. While many people choose Psi, I didn't.

One thing Illusion lacks is AoE damage. So, I want AoE damage out of my APP set if possible. I would also like some utility out of the other powers. Psi has a decent AoE damage power in Psi Tornado that might be a good choice if it weren't the same damage type. Primal has a good single target blast, but its only AoE is a fairly narrow cone. Plus, Illusion's lack of standard control powers means that you get limited benefit from Power Boost, the best power from the Primal set.

That leaves Fire and Ice. Fire has an early, fast and hard hitting AoE damage power in Fireball. Fire Blast is great, and does a little more damage than other APP blasts. The shield is Resistance, and then you have Consume (for Endurance Recovery -- needed sometimes) and/or Rise of the Phoenix, a self-rez power. Not essential, but useful.

Ice has two AoE damage powers in Frost Breath (a cone) and Ice Storm (a Rain-type power on a long recharge). Unfortunately, you don't have an AoE Immob to keep foes in the Ice Storm. Ice Blast is very good, and the shield is defense-based (which I like a little better). Hibernate is a wonderful "panic button" power that lets you recover both health and endurance by taking you out of the fight for a short time.

I chose the Fire APP on my main Ill/Rad, mainly for Fireball and Consume. But I use Fire Blast the most, and I suggest taking Fire Blast at 41. I have Ice on my second Ill/Rad and on my Ill/Storm. I have Fire on my Ill/TA, but he really needed Fire Blast and Fireball to light Oil Slick Arrow.

No, you cannot change the colors on APP powers at the present time.

I can't disagree with anything in Mr. E's post. It is simply a matter of choices -- what do you want out of your APP set? All of them will work.

I explain in my Ill/Rad guide why I feel that being able to take down foes quickly provides a substantial benefit to an Ill/Rad, by allowing an Ill/Rad to take advantage of spectral damage. That's why I like the Fire set -- the damage is front-loaded. Psi Tornado and Ice Storm are both DoT, giving the spectral damage time to heal back. I tried the Primal set on my Ill/Rad at one point (before Torrent was available) and found that I didn't use Power Boost all that often -- but then I usually keep EM Pulse in reserve as a "panic button" power. Different folks have different playstyles.

I have tried all of the APP sets one one 'troller or another. I love the Psi set on my Fire/Rad, who really needed IW, and makes good use of Psi Tornado. I like the Earth set on several of my controllers, like my Fire/Kin and Plant/Rad. Most of my */Storm 'Trollers take Ice for Hibernate. I think the Primal set is well suited on Mind Controllers who can use Power Boost for long lasting AoE controls. The APP set you choose depends on what you want out of it, but none of them are bad.

Not to do too much of a thread jack, but do you find you need Glue Arrow to keep mobs in Oil Slick or does it do ok by itself?

I use Glue Arrow on just about every group -- not just to keep the foes in Oil Slick, but generally to keep foes in the area of my Debuffs. Is it necessary to keep foes in the area of Oil Slick? I'm not sure, but an AoE slow is very useful for an Illusion controller who lacks AoE control powers.

I find I don't need it on my Earth/TA. OSA has a 90% runspeed slow, 25% def debuff (it doesn't really need any accuracy slotting) as well as knockdown, so it is quite effective at keeping stuff a-burning. Glue arrow wouldn't hurt, though, especially if you are fighting deeply purple foes.

I have the tech origin, but Fireball and Fire Blast give me more reliable lighting. And besides, Fireball + Oil Slick is simply awesome.