First, don't get the wrong impression from my above post. Gramarie is not at all mathy, unless you feel like adding in some advanced calculations like I usually do.

It's a subsystem allowing you to build and experiment with small components, in order to make big things. Instead of having all abilities small and compartmentalized, such as casting a spell that heals you, or buying a magic sword that does fire damage, it gives you base components, and let's you do with them as you will. With the right set of parts, virtually anything is possible.

If you want a lightsaber, put a piece of heat creating phlogiston inside a red filter that blocks the passage of heat, but allows all masses to move through it. Anything that moves through the filter will get seriously burned.

Want a laser powered by the faith of your zealot minions? Faith to energy transformer, energy to laser refractor.

Do you want to be an intelligent arm cannon? Breed a race of living tanks? Create your own plane and sculpt a world inside it? Invent the dnd equivalent of television, computers, and the internet? The more you learn, the more possibilities you see.
It's also got nukes and radiation, artificial intelligence, mind control that mimics programming, and portals (with the exploits that come with them).

It's also a world building tool, since a world with gramarie can be very different than a world without, and PC gramarists can make some big changes to the world.

Gramarie Compendium