I actually wanna write a book on this subject.
Dude gets an item with four gems around it (lets say a bracelet). The gem facing up is the power he can wield, and he can only activate one at a time.
1. Strength. He gains the strength of twenty strong men (lets say a strong man can bench 150 kilos, equating to 3 tonnes lifting power). He gains some endurance, but isn't invulnerable, especially to natural elements (i.e. drowning, fire, cold, etc).
2. Flight. He can fly pretty fast, but has no super-endurance, so he has to dress warm, not fly too high, and wear goggles so his eyes wont dry out.
3. Immortality. His body recovers from any wound and he cannot die. No other powers other then his initial strength (so headbutting a brick wall wont collapse the wall, just your skull - which would immediately re inflate and heal)
4. Invisibility. He goes totally invisible in every way, even by heat, but can still bump into stuff and people cant see him so they run into him all the time.
The thing about powers is that you need limitations to them, as well as guidelines. Its all well and good to rub the lamp and ask the genie for immortality, but he may just announce to the world that you're the first to prove magic is real. Your name goes into the history books and you are immortalized. Or, he makes you unable to die - but you keep aging. Stuff like that.
Super-Strength as well. Superman can only lift really heavy things because he can extend his invulnerability force field around it to keep it together, i.e. telekinetically (subconsciously). Otherwise, every time he tries to pick up a car, he'd just rip the frame off, because the car wouldn't be able to withstand its own weight and would fall apart. Good if you just wanna tear shit apart - bad if you want to lift something that's not solid in one piece.
Invisibility is a total no-no, only because if you wished to be truly invisible, you'd have to be blind too. We see by seeing the light bouncing off objects into our eyes, which process the image into something we understand. If you become invisible, light will simply pass through you, and you would not be able to see. And if you go past that 'light bending around you' business, dont. Same deal, except you're less invisible then you'd want to be. You'd look like a blur. Think of a Predator's invisibility. It was probably only applicable because of their helmets transmitting vision to their eyes by some means.
