The item drop forumla is complex and divided into multiple parts. (Percentages given are specific to this enemy.)
Chest selection - There is a 0% chance of dropping a gold chest. If it fails, there is a 0% chance of dropping a silver chest. If it fails, there is a 0% chance of dropping a wood chest. If it fails, no chest is dropped.
Squads - Only the last enemy in a squad may drop a chest. No matter which enemy it was, the chest will have the drops of the squad's leader (enemy number 1 of the squad's spawnpoint). The chance of getting a gold chest is tripled to 0%, and if this fails, a silver chest is 100% guaranteed if available.
Material selection
Wood chest - There is a 0% chance of dropping the first material. If it fails, the second material is dropped instead. If it succeeds, there is a 0% chance of also getting the second material as well.
Silver/gold chest - This enemy always drops the first material.
Other loot selection - The item selected is based on a straightforward "relative odds" selection, for both the item category and the item in the selected category. If an item from this category has been selected already, duplicates are not allowed.
Crystal strength - This enemy's crystals will vary between 80% and 90% for the first attribute, though there is a 25% chance of it being between 92% and 99% instead. If there is a second attribute, it will use these ranges divided by 2.
As a result of these rules, the resulting probabilities can vary wildly from the raw percentage values, but it is the raw values that matter for effects that alter them, such as Riki's chest-manipulating skills.
When a summon art is used, the user goes to its own spawnpoint and looks up the index matching that of the summon art, which spawns all enemies attached to that spawnpoint. As a result, what spawns is dependent on both the art used and the enemy's original spawnpoint. This table is being drawn because the enemy has a summoning art equipped, regardless of whether there's anything in it for said art to use.
This table only displays enemies and spawn probability. For further details, see the enemy and spawnpoint pages.
Yaldabaoth's talent art, Bionis Slash X, is unique in many ways.
It is shown as the Mechonis atttacking the Bionis, rather than Yaldabaoth attacking the party, and deals infinite damage. In "reality", it hits all around Yaldabaoth and automatically defeats all party members regardless of any other effects.
Despite being level 10, a level 10 Monado Shield cannot block it. (Shulk can't put a shield around the entire Bionis, and it isn't part of the party anyways.)
It triggers a vision 120 seconds (2 minutes) long, far longer than any other battle vision.
When the above vision occurs, the Save Bionis story quest is obtained.
Dazing Yaldabaoth deletes the vision entirely, rather than simply changing it to a different art. As Yaldabaoth will be invincible for 300 seconds (5 minutes) from having used Energy Replenish, the only way to do so is by completing the story quest, which forces daze outside of the battle system (and removes the limit on Yaldabaoth's HP so it can be defeated).
Break
Pierce
Topple
Instant Death
Daze
Strength Down
Slow
Ether Down
Paralysis
Agility Down
Bind
Phys. Def. Down
Lock-On
Ether Def. Down
Sleep
Arts Seal
Confuse
Aura Seal
Boss 
Topple (3.0s)
Arts Seal (20.0s)
Bind (10.0s)
(100%)
.gif)