Mithril dragons can be found and fought in the Ancient Cavern. To access the Ancient Cavern, the player needs to start the pyre ship section of Firemaking in Barbarian Training. Be wary as these monsters are extremely powerful. Their release broke the King Black Dragon's long-standing record as being the strongest dragon in RuneScape. It is strongly recommended to use antifire potions in conjunction with an anti-dragon shield (or a Dragonfire shield) when fighting these along with the appropriate protection prayer.
The ability to be assigned mithril dragons can be purchased for 80 Slayer reward points. Once unlocked, they can be disabled, but players must spend another 80 points to unlock them again. Players also must have entered the Ancient Cavern at least once to get mithril dragons as a slayer task. 
Slayer Masters offer to convince mithril dragons to drop their bars in noted form while on a slayer assignment, for a cost of 200 slayer points.
Mithril dragons can be found on the top level of the Ancient Cavern. Note that dwarf multicannons are not allowed in the Ancient Cavern.
To access the Ancient Cavern, one must have completed the first part of Barbarian Firemaking training and then talked to Otto about pyre ships. After the conversation is over, the player can now go in the whirlpool. Upon entering, one must climb down stairs and then run south to a set of stairs leading up to the mithril dragons.
- ↑ https://twitter.com/jagexash/status/713721069136449537
- ↑ Dropped in bank notes if players have purchased the Duly noted unlock for 200 slayer reward points and are on an active slayer task of mithril dragons
Item Quantity Rarity GE market price Rune battleaxe 1 Common 24,623 Rune dart(p) 14 Common 15,204 Rune mace 1 Common 8,324 Rune full helm 1 Uncommon 20,750 Rune knife 8–18 Uncommon 2,296–5,166 Rune spear 1 Uncommon 12,103 Dragon full helm 1 Very rare (1/32,768) 38,906,171
Item Quantity Rarity GE market price Blood rune 27 Common 7,263 Rune javelin 8 Common 1,288 Dragon javelin heads 15 Uncommon  15,195 Rune arrow 8 Uncommon 960 Runite bolts 10–21 Uncommon 3,840–8,064 Soul rune 10 Uncommon 1,470
Item Quantity Rarity GE market price Prayer mix(2) 1 Uncommon 5,071 Superattack mix(2) 1 Uncommon 656 Super def. mix(2) 1 Uncommon 785 Super str. mix(2) 1 Uncommon 1,166
Item Quantity Rarity GE market price Coins 600–876 Common Not sold Runite limbs 1 Common 9,323 Runite bar 2 Common 24,870 Shark 1; 6 Common 738–4,428 Chewed bones 1 Uncommon (1/42) Not sold Ancient page 1 Uncommon (1/64) Not sold Clue scroll (elite) 1 Rare (1/350) Not sold Draconic visage 1 Very rare (1/10,000) 7,662,377
Rare drop tableIn addition to the drops above, this monster has access to the standard rare drop table.
Show/hide rare drop table Item Quantity Rarity GE market price Coins 3,000 Rare Not sold Loop half of key 1 Rare 9,984 Tooth half of key 1 Rare 11,768 Uncut sapphire 1 Rare 661 Runite bar 1 Rare 12,435 Unknown talisman
1 Very rare Error Nature rune 67 Very rare 13,802 Rune 2h sword 1 Very rare 37,967 Rune battleaxe 1 Very rare 24,623 Uncut emerald 1 Very rare 872 Law rune 45 Very rare 10,530 Death rune 45 Very rare 10,395 Steel arrow 150 Very rare 4,050 Rune arrow 42 Very rare 5,040 Adamant javelin 20 Very rare 1,020 Rune sq shield 1 Very rare 22,680 Dragonstone 1 Very rare 12,129 Silver ore 100 (noted) Very rare 7,600 Uncut ruby 1 Very rare 1,509 Rune kiteshield 1 Very rare 32,217 Dragon med helm 1 Very rare 59,320 Rune spear 1 Very rare 12,103 Shield left half 1 Very rare 65,634 Dragon spear 1 Very rare 37,414 Uncut diamond 1 Very rare 2,838 Rune javelin 5 Very rare 805
- Prior to the release of Dragon Slayer II, mithril dragons were brighter in colour. Their old appearance was given to rune dragons to make them appear more like the metals' true colours.