When the staff is charged with a spell, it casts the spell as if the runes are in your inventory. It is also possible to manually charge the staff with up to 1,000 casts of the chosen spell. Charging the staff will require players to use the exact type of runes required to cast it; combination runes such as dust runes, steam runes or lava runes will not work. The staff can save inventory space taken up by runes if you are willing to sacrifice the better accuracy of alternatives like the chaotic staff.