Summoning monsters, according to the game world in Dark Summoner, is accomplished by transporting monsters in from alternate dimensions in order for them to do the Summoner's bidding. This has directly and indirectly led to the destruction of the world as we know it, making the world of Dark Summoner a bleak, post-apocalyptic wasteland, controlled by the three powerful Guilds.
Practically, it is the mechanic by which players can (usually randomly) summon more-or-less powerful monsters to add to their collections.
There are several different types of Summons: (Note that relative odds of receiving different tiers have not yet been calculated for the various types of Summons. Please inform us of any research done, either in the Talk page or by adding directly if you have statistically significant data.)
Normal Summons
This is by far the most common type of Summon that a player will encounter and use. It can be obtained through Ally Points, daily bonuses, stamp collections, social bonus and other special events.
Type of monster summoned: C-rank through A has been observed at this time.
Note: Please note if you have obtained a higher-rank monster than A on the Talk page
Dark Summons
Dark Summons are available as Premium content, from special events such as daily stamp collections or from other various special events or awards.
Type of monster summoned: B-rank through AAA has been observed at this time.
Note: Higher rank monsters (AA-AAA) appear VERY infrequently so players should not expect to acquire one of these monsters with ease. That being said, there have been reports of players acquiring AAA rank monsters through free dark summons obtained in events so there is still the possibility of obtaining these entities.
Special or Unique Summons
Special Summons are assorted kinds of Summons available through a number of special events, achievements or awards throughout the game. Sometimes they award a specific tier of monster, or have a chance of awarding a unique monster more powerful than Dark Summons, or award a specific monster.