A Firestone is a wand-slot (technically a relic), conjured item created by the warlock [Create Firestone] spell, allowing warlocks to enhance their main hand weapon to do additional fire damage and gain a fire spell damage bonus buff for as long as the firestone exists. These conjured items disappear if logged out for more than 15 minutes.
Ranks
Firestones/table
Tactics
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External Links
Wowhead Firestone info.
Thottbot Firestone info.
Allakhazam Firestone info.