Ascension keystone

There are six ascension keystones, dropped by the slayer monsters in the Monastery of Ascension:
 * Ascension Keystone Primus
 * Ascension Keystone Secundus
 * Ascension Keystone Tertius
 * Ascension Keystone Quartus
 * Ascension Keystone Quintus
 * Ascension Keystone Sextus