Rafael is not strictly human any longer. His 'body' is a cloud of particles that are made, on a subatomic level, of pure telekinetic force that is wrapped around a permanently disembodied astral form. This makes his shape almost infinitely malleable, limited largely by his imagination and subconscious barriers. He can add and subtract height, weight, density and mass by adding to and subtracting from the number and properties of the pseudo-particles that make up his body.
However, the amount of focus and power it takes to keep him incarnate and the complexity of the simulation is so vast that his psychic powers are permanently functioning as a sort of autonomic system and life support. The mechanism of control for his abilities and that life-support function on a subconscious and autonomic level, entirely out of his control. And indeed, tinkering with that could very cause him to cease to exist, like the old story about the man who focused too much on the mechanism of breathing and thus forgot how to do so.
Rafa also doesn't have a physiology like a normal person. While he has pseudo-nerves that allow him to have sensory feedback from the world and he can break down food and water into harmless subatomic remnants via his autonomic use of his powers, his form responds to damage from physical and electromagnetic sources by being shredded, torn, shattered and dispersed, rather then bleeding or suffering broken bones. He can ripped to shreds or blasted to bits by sufficient force and rendered unconscious or non-functional by attacks that depend on doing damage over a surface area or structurally, as well as losing large amounts of pseudo-particles to trauma.
In other words, cutting, stabbing, shooting, optic blasting and blowing him up will knock him out, depending on the force involved. He is functionally immune to human-level punching, though a certain level of super-strength (detailed below) will knock him silly.
Rafael's control of his body is sufficient that he can shapeshift to imitate other people well enough to pass a casual inspection but not well enough to pass biometric scans. The voice will be his own, there will be no finger or palm prints, he has no odor to speak of and most especially his eyes in any form are wells of blue-white psionic energy. Rafa can manifest claws, fangs, wings and other animal or monstrous features, but they will appear cartoonish and stylized, rather than being mistaken for belonging to an anthropomorphic creature.
He can also add functioning muscle and even imitate specific mutation features, like Nightcrawler's skin, fur and tail and Wolverine's claws. (He can even give them the density and sharpness of metal (adamantium is out of his range) but cannot imitate powers like Wolverine's sensory abilities or Nightcrawler's teleportation. It is also worth noting that he can distend and distort his own or an imitated form, which he usually does for comic effect. He can also imitate clothing and personal items out of the substance of his own pseudo-particles but anything mechanical or electronic will just be a mock-up, non functional, beyond the level of very simple items like shovels, hammers, knives, etc. He cannot separate any of these 'items' from his body. They are a part of him that just looks like the item being imitated.
He can shift the form of all or parts of his body at will.
Rafa heals by generating more psionic pseudo-particles and aggregating them back around his astral form. This takes time and effort but generally, for now, the rule of thumb is that he has a low-level healing factor like the early appearances of Wolverine. A minor wound will knit up in minutes, a major one in an hour, a life-ending one overnight and if blasted to bits, it may take him twenty-four hours or more to regroup enough substance to form a body. He is immune to all forms of healing except those that are specifically spiritual or psionic in nature. (This includes the Shi'ar devices in the Xavier med bay). To kill him outright, one must use magical or psionic means.
n terms of quantifying Rafa's powers, the rule of ten is useful. His limits occur in multiples of ten for now.
His maximum weight is about a thousand pounds. The minimum is about a pound.
His maximum area is about ten cubic feet and his minimum area is about a square foot. (He can thin out the particles enough to go semi-flat, call it 1/10 of an inch minimum thickness, like fine cloth.)
When in human form, he can distend a limb or area of his body by about ten feet, though he can use this to somewhat disconcerting effect (like stretching an ear or his optic nerve bundle to hear things under a door or see around a corner).
He can add extra muscle and mass to lift up to five tons (10,000 pounds).
When in baseline form, it takes 10 tons or more force to disrupt/damage his form by blunt force trauma. (But cutting/blasting/etc will still disrupt his pseudo-particles.)
The maximum density he can give himself or any part of himself is about 10 times stronger than bone (which is roughly steel) and the minimum is 10 times weaker (paper). At those density levels, his body has the properties of those materials. (Hardness, durability, etc.)
Rafa is a being of pure mental/spiritual energy who creates an artificial body that he wears like a glove. The glove can be ripped without harming the hand within. But if the hand is shattered, the glove doesn't matter. He is exceptionally vulnerable to attacks the target the mind and soul and has no native psionic defenses whatsoever. Any damage done to his astral form shows up on his body. Telepathic blasts and soul-fire affect him as physical explosions or burning would and take human-long recovery periods. In addition psionic or spiritual effects that are physical manifestations of psychic or will power can affect his astral form because his pseudo-particles are tied directly into it. Something like Psylock's psi-blade or Julian's TK would affect him directly and do damage to the astral form.
Enough damage to physically kill a human will disrupt his astral form fatally and he will die. (Permanently, this time.) Happily, his astral form regenerates at much the same speed as his pseudo-particles. (Though he has to heal up the astral form before fixing the physical one.)
It is also worth noting that his astral form is pure psychic and life force surrounded by an artificial shell. This means that he is essentially a walking big gulp for psychic and life-energy vampires and those who can see and feel those energies will notice that and perhaps decide he is easy prey. His astral form heals at much the same rate as his physical one, however, so if he is not completely consumed/disrupted and can get away, he will be able to heal. (Though his astral body must heal first and then reconstitute the psuedo-particle one.)
Rafa no longer has to breathe but he doesn't know that and will pass out from psychosomatic trauma if he thinks he's been choked out, drowned, strangled, etc. Getting rid of this limitation will require some mental readjustment on his part.
Rafa's shapeshifting could allow him to assume non-living but animate forms as well with somewhat anthropomorphic features. He is unaware of this potential at the moment but it is included for power duplicators and those who can read/control the powers of others. For instance, if he changes shape to look like a trash bin, it's going to be a trash bin with little cartoon-style legs and arms and his own face flattened into the material, with his characteristic glowing eyes. (Think Morph, Slapstick and Plastic Man for this).
Given his ability to control the density and distribution of his pseudo-particles, it is even possible that he could form coherent liquid forms or even become a sentient gas or even phase through materials. He will never be able to create complex, working machines out of his substance unless he gains a degree in mechanical and/or electronic engineering, but again, a power duplicator may have the skills required. Note that Rafa does NOT have access to these abilities when starting and each aspect would be something to be apped for power upgrade approval.