Octograve

From The Discworld MUD Wiki

The octograve command uses a staff (walking stick also works) to inscribe a magical symbol on the floor. This costs 50 gp and uses your magic.items.held.staff skill. The command is learned from Runes at about 50 levels or so of staff skill.

Many spells require octograving as preparation to their casting (this will be mentioned in the spellcheck info).

It has also been suggested that octograving improves the chances of success when casting certain spells.