Runesmithing

Runesmithing is how you make the runes that Magic spends. You mine glimstone, carry it to a rune's altar, and carve it into runes there. Every altar stands out in the world inside a ring of standing stones.

Getting started

Start with the quest The Pull of the Charm from Orrin Vell (Vell's Staves, Thornbury). It gives you a Gale charm and ends with the glimstone pit open to you; after that Vell sends you down whenever you ask.
Take a pickaxe. The pit's rocks never run out. Below Mining 30 they give glimstone; from 30 on they give pure glimstone. A portal at the west end of the pit brings you back up to Thornbury's square.
Or buy glimstone: the magic shops sell it at 5 coins a stone (Rook's Runes in Emberville, Merrow's Staves in Wickstead, Brenner's Staves in Kilnhold and Vell's Staves in Thornbury), one within a walk of every altar that takes plain glimstone. Goblins, raiders, highwaymen, the dead and most creatures that carry runes drop it too, more the tougher they are. Pure glimstone comes from the pit only.
Both kinds stack 99 to an inventory slot.
An altar only answers to someone carrying its own charm. Right-click a charm and choose Locate and it tells you which way its altar lies (and whether it's below you). Lost your Gale charm? Vell has a drawer of them.
Click an altar to Carve. Every stone in your pack that the altar takes becomes runes at once. The altars up to Sinew's take either kind of glimstone; every altar after that takes pure glimstone only.
The higher your level, the more runes each stone makes. XP is paid per stone, not per rune.
Circlets: make a silver circlet from a silver bar at a furnace (Crafting 23), then use it on an altar with that altar's charm in your pack. The charm goes into the circlet, and wearing it answers the altar just as the charm would, without taking a pack slot.

The altars

Rune	Level	XP a stone	Stone	More runes a stone	Where	Charm dropped by
Gale rune	1	5	Either	2 at 11, 3 at 22, 4 at 33, 5 at 44, 6 at 55, 7 at 66, 8 at 77, 9 at 88, 10 at 99	The East Meadow	Mudfoot goblin
Thought rune	2	5.5	Either	2 at 14, 3 at 28, 4 at 42, 5 at 56, 6 at 70, 7 at 84, 8 at 98	The Emberville road	Mudfoot raider
Tide rune	5	6	Either	2 at 19, 3 at 38, 4 at 57, 5 at 76, 6 at 95	Wickstead	Highwayman
Stone rune	9	6.5	Either	2 at 26, 3 at 52, 4 at 78	Stonecote	Mudfoot raider
Ember rune	14	7	Either	2 at 35, 3 at 70	The Cinderwaste	Highwayman
Sinew rune	20	7.5	Either	2 at 46, 3 at 92	The Harrow	Ruin skeleton
Star rune	27	8	Pure glimstone	2 at 59	The Dunes	Dune raider, Fen wight
Wild rune	35	8.5	Pure glimstone	2 at 74	The Harrow	Grave shambler, Mudfoot warchief
Bloom rune	44	9	Pure glimstone	2 at 91	Sablewood Isle	Barrow warden
Oath rune	54	9.5	Pure glimstone	2 at 95	The Cinderwaste	Delve haunt
Grave rune	65	10	Pure glimstone	2 at 99	The Harrow	Drowned mourner
Heart rune	77	10.5	Pure glimstone	—	The Sallowfen	Rift hound
Shade rune	90	12	Pure glimstone	—	The Fen Hollows (below ground)	Drowned ringer, Rift wraith
Fury rune	95	8	Pure glimstone	—	The Rift (below ground)	Rift-sworn, Rift wraith

For example, at level 22 each stone carves into 3 Gale runes, so a full pack of 27 stones makes 81 runes and pays 135 XP.