1. Add some advanced combat mechanics. The apply PI to do more dmg with your own power set is not enough. Consider something like one person casts an electrified PI and if another person immediately casts an earth power that some advanced dmg effect occurs (have it create a secondary effect like Grounded that is based on timing the second power to hit in window (think wm burst but across two people). Another option would be have to people activate WM combos one after another in a certain order to have an additional effect happen. Right now combat is simply power 1,2,3,4, block, block, lunge, repeat. 2. Either eliminate or significantly increase the cost to replay the latest content. So many people spammed the new content right out of the gate that they hit max CR in a very short time. Once they hit CR, they disappear until next content which makes the game feel empty. 3. Strategically stagger release of content so that it lasts longer. For example, don't release elite mode until a month or two after the basic raids out. Because people spam content immediately upon release, they are in elite content within a week. 4. Merge hero and villains queues for PVE. Make it a Suicide Squad for PVE raids. Have the content reflect whichever faction has the most players or make it random.
I'll say it like this: I like the basic idea, but could you expand on it a little bit more? Like give an example as to what this "Advanced Power Interaction" would look, like, what effects it would have, and what the team effect of it would be. Personally, I would ADORE to remove replay badges from the game (or make its only use to buy feats). But unfortunately, I think that's where most of their revenue comes from ever since they first introduced the concept. They shot themselves in the foot with it, and they can't remove it without either updating the market with more desirable styles and items or finding some other way to make a steadier income along with subs (because let's face it, not everyone has the choice or opportunity to sub. They need to make premium players feel comfortable spending money as well besides crappy "escrow tickets" and "local authority" or "cosmic/sequined" styles of normal items [outside of cosmic skin cause its cool -w-]) and the usual "flavor of the month" crowd who blow cash to scoreboard chase like hell. Honestly, the only way to increase replay value of content (besides removing the idea of people running it for items instead of fun) is to add in dynamic mechanical values that change the way the instance works every. single. time. But that would be tough to work into such a thing as most players don't play for fun. They play for self-gratification and to lord over people just because. This could only be done logically against enemies of both factions. Brainiac, League of Assassins, Red Lanterns, maybe Black Lanterns (let's face it, Nekron and Black Hand are on their own side), and Morrow and his trash heaps since Villains beat on him for screwing over Joker and heroes do it because they have sticks up their butts.
For your 1. You may need in-game icons to alert players when the combo is possible to execute. I would not recommend relying on party communication to pull these moves off.
Yeah we would need an icon or sound or both similar to the weapon mastery sound. Some games make the required powers look much different and noticeable so that folks know what to do. Think of the possibilities: Fire and Ice = Steam: Person A drops Flame Meteor (the boulder power) followed by Person B dropping Ice Boulder = Steam Cloud Elec and Earth = Grounded Sorc and Celest = Mystical Gadgets and Munitions = Frag Grenade or Gadgets and Quantum = Worm Hole Rage and HL = Rainbow! Nature and Mental = Illusionary poison spiders I could go on. For weapon mastery it could be: Person A uses Solar Flare followed up by Person B using Explosive Arrow. Or, Person A uses Explosive Arrow Mastery and Person B casts Inferno to cause Flaming Arrows
