Leaf is a Diablo 2 Resurrected runeword created by combining tir + ral into a 2 socket staff. It requires at least level 19 to equip.
Staves can have up to 3 auto mods specific to Sorceress spells ranging between +1 and +3 to skill level. Therefore, you should look for a 2 socket staff with at least some +skills that your build uses. An easy way to quickly find good staves is to shop with Drognan in act 2. You can reset his shop by exiting and re-entering town.
Did you know? It takes on average 4 countess runs on Normal difficulty to get this runeword.