Leaf is a Runeword "TirRal" in Diablo 2 Resurrected (D2R). It requires these 2 runes to be inserted into a socketed item in the exact order: Tir + Ral . The eligible bases for Leaf are the following: Staves . This is the only Runeword in the game that has +X to Fire Bolt (Sorceress Only) attribute.
LeafLeafShort Staff
Tir · Ral
Two-Hand Damage: 1 to 5
Durability: 20 of 20
Required Level: 19
Increased Melee Range: 1
Base Attack Speed: -10
Adds 5-30 Fire Damage
+3 to Fire Skills
+3 to Fire Bolt (Sorceress Only)
+3 to Inferno (Sorceress Only)
+3 to Warmth (Sorceress Only)
+2 to Mana after each Kill
+(2 - 198) Defense (Based on Character Level)
Cold Resist +33%
Socketed (2)
Trade items on d2trader.net

How to obtain Leaf

The fastest way to get this item on Battle.net is via trading, you can use the Item Price Checker to see how much Leaf is worth.
Another way of getting this Runeword is by farming the runes and the base. Find the drop rates of these items in the Item Database.

Leaf bases

The best base for Leaf is Short Staff. Below is a list of all eligible 2 socket bases for Leaf.