Biff Pow

I like Spring Attack. It's not particularly useful because of its long recharge, but it's fun to leap into a crowd now and then. I don't know if Laser Eye Beams fits with your concept but Energy Mastery is a good epic pool choice. Focused Accuracy helps with +Perception and ToHit Debuff resistance, though Super Strength doesn't need that as much as other sets. And obviously some +Regen and +Recovery from Physical Perfection.

One nice thing about Kinetic Melee if you're looking for Defense bonuses- there's lots of places to slot the Winter IO sets.

Basically, yes. Fire/Cold isn't hard, pretty much every purple set gives 6% resists, some also give Psi/Toxic. Shield Wall and Unbreakable Guards for E/N, and the Tanker sets for everything.

You can get a lot of resist and defense bonuses from Invention Sets, and then with the Might of the Tanker proc get up near 90% resistance to everything. But honestly, once you're up to the 70s or so in resists (plus capped S/L), you're already taking so much less damage that 90% is overkill. Mids numbers can be misleading, or use really weird builds that aren't fun to play, I prefer to go by in game stats. Here's my Inv/SS in a fairly basic situation: two enemies in Invincibility range and one stack of Might of the Tanker.

60% is decent Accuracy. In situations where you're missing a lot, it's usually +ToHit that you want (or ToHit Debuff resistance), not more Accuracy.

Sonic Blast kind of does the opposite- put the minions and Lts to sleep with Siren Song while you deal with the boss. And it's auto-hit.

Invulnerability has four auto powers and just three toggles (which are pretty light on endurance.) It doesn't really need a recovery boost.

This is my final build, so it's very purpled-out. Blaster SonicEnergy.mbd

I'm all for a toggle, but I know how upset some players get when you threaten to take away their double-stacked Rage (which I think it overrated myself.) A mutually exclusive option would be a better idea. I agree, but I also don't think Fiery Aura works thematically for Stalkers. Keeping ATs theme-based kind of went out the window years ago.

My problem with the -damage crash is it just feels kludge-y. I think an increased endurance crash gives the same effect (better calm down) but it would feel more natural than 'no damage for ten seconds.' Yes, there are other things to do during those ten seconds and powers that will work, but mostly you're just hovering over the key for Footstomp or KO Blow waiting for the crash to end.

Get rid of the -damage and -defense and increase the endurance crash. Increase the damage of the first three attacks. They should not do less damage than Fighting Pool powers.

I think a reasonable change is Hurl remains a single target attack but causes AoE knockdown like Gravity Control/Propel.

While I haven't done it on Homecoming (just don't have the time), making AE missions is a lot of fun and its own type of content. If you ever feel bored with the game, start making up your own stories.

I find there's a balance where chasing a certain bonus too much can hurt your build in other ways, or just make it not as fun. I see a lot of builds that skip fun powers (like Boggle in Psi Melee) because they have to fit in so many pool powers. My Blasters generally end up around 30% defenses and that works great. If I tried to push it into the 40s I would have to give up offense or utility and end up worse off.

My Inv/SS Tank now has a 90% damage bonus with Rage running instead of 100% which barely makes a difference except I really liked that round number. (Yes, I could find another 10% in bonuses but I like my build as is.)