Buy OSRS Anti-dragon shield
The anti-dragon shield is a classic defensive item in Old School RuneScape. It gives partial protection from dragonfire, cutting the max hit of most dragon-breath attacks by about 80 percent. It also stops Elvarg from badly draining your combat stats. Pair it with an antifire potion and you get full protection from standard dragonfire.
You need to have started the Dragon Slayer I quest to equip it. Its melee and ranged defence bonuses are close to an iron sq shield, but it also gives Magic defence and has no offensive penalties. That makes it a solid all-purpose shield and the best shield in slot for free-to-play mages.
The shield can be upgraded later. With 90 Smithing, a hammer, and an anvil, you can attach a draconic visage to make a dragonfire shield and earn 2,000 Smithing experience. Oziach can help make it for 1,250,000 coins if your level is too low. After Dragon Slayer II, a skeletal visage can be fused to it instead to create a dragonfire ward. Both upgrades keep the anti-dragon shield's dragonfire protection.
This shield is a must for any trip to fight dragons, from quests to Slayer tasks.