[PTTG]

Here's a few interpretations of "Mana comes from life."

Forest Mana: Plants increase the local mana level. Deserts, glaciers, and mountains above the treeline are No Mana. Grasslands, shrub, and so on are Low. Most forests are Normal. The densest parts of rainforests reach High Mana.

Settlements are complicated. Anywhere under the cover of a tree which is itself part of a major forest has that forests' mana level. Artificial structures that overwhelm the natural character of an area lowers the mana level by one. Taken together, no major settlements have High Mana.

Oceans are unpredictable. Kelp forests and plankton blooms count as forests. Coral reefs are effectively rainforests and can have High Mana. But traveling the surface of the ocean doesn't help you very much.

All mana is plant aspected.

Blood Mana: Life stores mana, and it accumulates as you go up the food chain. The baseline effective Mana Level sits at Low. Magery includes Energy Reserve (which can only be used for Magery) and this reserve only recharges via a number of magical processes which largely revolve around the use of fresh blood. The higher the trophic level, the more effective it is.

Feudal Mana: To swear allegiance to annother is to grant them a portion of your power. In an otherwise Low Mana world, each step up the rank of feudal hierarchy is a level of Magery, starting with Knight.

One more general one:

Mana Islands: Mana is alive. It flows, its wellsprings move. They die and are born. At any given time, there are about 20 mana springs. They are High or Very High Mana zones anywhere from a few miles to 50 miles across, with concentric rings of lower mana where each band is about 100 miles wide. These regions move at a rate of about 100 feet per year... usually. Sometimes they move more than a mile per year, and occasionally much more. The rest of the world is No Mana.

Despite their tendency to last only decades in a place, the High Mana zones are natural places for cities. At least, they are among the more adventurous types.

Bonus:

Sparks Some beings are sources of magical power. They radiate it out, imbuing their homes and surroundings with power. The basal mana level is Very Low, but the presence of these sources can dramatically raise the level of mana. Sources take many forms, often (but not always) in proportion to their power. Wisps and faeries usually produce a gentle, localized magical field. A mighty giant elk or leviathan may raise the mana level for miles. These boosts combine in a complicated way (sources of the same type don't stack, but differing ones do).

Sources are never mages, and groups which can include mages are never sources.

Another!

Aurium The transmutation of metals is the key to all magical workings. At the bottom of the chain is coal or soot, with light and soft alumwhite being the next material up. The chain of magical power continues upward through ilmonite, iron, cobalt, copper, tin, and a number of others before reaching scented silver, platinum, gold, and quicksilver. Each step up the chain involves an investment of magical power, and each step down releases it for use...