Buy Them at the grand exchange, craft them, or buy them from the mage guild.
Mostly Fire runes but Law runes and Air runes are not far behind them.
I do not know the complete list however, I do know that these monsters do drop law runes: barbarians dark wizards wizards cockroach soldiers
The monsters that drop law runes are the giants (all) Catablepons and dark wizards. If don't won't to kill thaws u can buy then in wildy at magic shop.
That is "telekinetic grab". Look in the spellbook. You need magic level 33. Once you have that, you need law runes and air runes to actually cast the spell.
You can make 16k-23k an hour doing law runes and nature runes are about 20-24k an hour.
There is no staff like this.
runescape
The answer is yes. You do need to supply your own runes.
Nature/law running is probably your best bet, you may want to check the runescape forums for more information regarding this. ( Runes section )
The question is quite unclear, but if you mean, what type of essence is used to craft law runes in Runescape, you use Pure Essence. Hope that answers your question.
They could be anywhere throughout RuneScape.
Crafting Water Runes.