There are four Dungeon Stratums; Brown, Green, Blue and Red. Runeborn monsters' runes depend on the stratum they're dug into. If a rune is located in the first (brown) dungeon stratum, it can only spawn a Wookiemon, Diabro, Idle Wookiemon or a Brahzuzu. If a rune is in the second (green) stratum, it can spawn a Golem, Talos, Blob or a Majin. If a rune is in the third (blue) stratum, it can spawn an Ash Lady, Phantom Lady, Scary Lady or a Crystal Lady. If a rune is in the fourth stratum (red) it can spawn any of the monsters mentioned above, depending on the nutrients/mana the rune has absorbed.