metra.2401

Sigils and runesYou use the forge to combine four runes or four sigils of the same rarity (either all masterwork, or all rare); it does not accept a mixture of the two types. Combining runes has a chance of returning account bound runes of the types that are found in Dungeons, for example, Superior Rune of the Monk. Superior runes and sigils cannot be combined in the mystic forge at all, but are used in some specific recipes, such as gifts. You can combine 10 Piles of Lucent Crystal, a Symbol of Control, a Symbol of Enhancement and a Symbol of Pain to receive a random superior sigil, or 10 Piles of Lucent Crystal, a Charm of Brilliance, a Charm of Potence and a Charm of Skill to receive a random superior rune. For a possible list of sigils and runes that can be output by the mystic forge, see Mystic Forge/Sigils and Runes. https://wiki.guildwars2.com/wiki/Mystic_Forge

The Mystic Forge is asking for a whole stack of every item when you try to combine charms and lucent crystals to form armor runes.