Gold has a number of magical abilities and the means to grant spells and favors to others, to an extent -- many of these are plotting-required and should be opted in. Please note that for things like basic magic/tk/offensive spells like fireballs or transformation, I need your word here whether that's a hard no but in most cases I will PM before dropping something like that in a thread.
Wards/Potions/Charms - These are usually complicated and require specific objects or ingredients to do so, and said ingredients can and often do operate on fairy tale logic. For example: Rumpelstiltskin can cast a protective ward around an area, but it requires using special chalk. That chalk would have had to have been fortified in some way -- perhaps imbued in Holy Water or carved out by a craftsman who never told lies. He managed to bottle the essence of magic by getting a hair each from a couple in true love, which creates its own magic, thus allowing himself to access his powers again in the world without magic. He can track a person if he has an object that belonged to them, provided they're on the same plane and/or not dead (at the time). He could create a specific ward or charm against or for a person if he has a possession of theirs or something as simple as a hair. Even their name, if he uses it correctly, can be put into a spell. (He used Emma Swan's birth name, for instance, as a trigger to reawaken himself from the first curse in the series.) What's important, and what probably limits these things the most, is that he can't take any of these things without permission. They have to be given freely or won fairly by someone. In fact, most of his more impressive miracles that people buy don't work unless there's some form of consent from someone involved -- usually a signed contract. Now, whether the buyer fully understands that contract is their problem. He needs consent -- dubious consent counts. Most of these are plot-specific spells. They would require me to plan with other people and seek permission beforehand and would take time for Rumpelstiltskin to put together. For instance, if a spell/ward/charm/etc were to require "a heroic weapon," these components could mean several things. A heroic weapon might involve nabbing, say, Mjolnir from Thor (which is an object in his vault in the series, btw), or a pen belonging to an adventure writer.
NERFS: I have none set in place because these limit themselves through plotting. I will not move forward with any of these without player and mod permission.
Telekinesis/Immobilization - Gold can throw invisible force, lift people and objects, and also paralyze people to stop them interfering with him or running away. It lasts for as long as he's concentrating on it.
NERFS: Will not until otherwise agreed upon by mods, be able to lift anyone or anything larger than he is without extra, concentrated effort.
Healing - He can heal virtually any injury provided the person in question is still alive.
Fireballs - He can make balls of fire in his hands, and he can throw them.
Teleportation - Gold has shown the ability to teleport to places that he knows. He would not be able to go behind locked doors if he's never been on the other side before or places that otherwise he might be warded from; this includes restrictions laid down by contract or written law.
Transformation/Polymorph - He can transform people and objects -- he can't grant immortality, but he can make you younger, or age you. He can transform people into different animals, or into different people. He spins straw into gold. He turned a man into a snail just so he could step on him.
NERFS: None of these things will be done to people or other people's belongings without player and mod permission where required.
Youth Eternal - Gold is also incapable of being killed, save by the Dark One's dagger, which didn't come with him. He will heal from virtually any injury or sickness unless he is cut off from his magic. (Example: being sent out into the world without magic, beyond the borders of Storybrooke, would render him powerless and capable of being killed or poisoned. The latter is effective in that any poison or sickness he incurs, if allowed to run their course long enough to weaken him too much, even if returned his powers won't heal him and another means to cure him must be found.) Note: The dagger will not appear in Duplicity unless for agreed-upon, plot reasons, because its holder can also command him.