Monster Balls are utility/tool items that work like Pokéballs from the Pokémon series (if not a carbon copy or tribute of it).
They can rarely be bought off general/goods vendors in towns, as well as Moyer the Crooked.
You can obtain six Level 5 monster balls by accepting the Ambitious Scientist's quest in Port Kapul (though if you want to complete the quest, you must give 5 back (of any level)).
Monster Balls come in different levels, the level indicates the maximum level of monster the ball is capable of holding. Higher level balls are more expensive.
Filled monster balls containing same creature will stack only if balls used were of same level themselves.
How to use a Monster Ball[]
The first thing you must do to use a Monster Ball is to find a monster of appropriate level for the ball you have. You can reference the breeding list for a complete list of monster levels. You must be able to severely damage the monster to the point where it is at a sliver of health (5% or less) without killing it. This is rarely a problem for a strong monster, but it can get quite tricky if the target is significantly weaker than you. Poisoning (potions of poison/dye/antiseptic or touch of poison special action) or bleeding (chestnuts/shurikens) are your best bet. Alternatively you can spend a feat to get a knockout special action for a guaranteed non-lethal attack or dip some expendable weapon in acid several times to give it a damage penalty from negative enchantment level. After you have damaged the monster enough, you can use the Throw command to throw a Monster Ball at it. If the ball hits:
First it will check if target's health is low enough. If not you will get a message telling you so. The ball is placed on the ground.
If health levels are acceptable, it will check target's level. If its too high you will get a message that ball is too weak to do anything. The ball is placed on the ground.
If both conditions above are satisfied, it will capture the monster and fall to the ground on the square the monster was standing on.
Monster Balls cannot be used to capture <> or {} enemies (note that Chess Pieces are only <> enemies if they are double bracketed, e.g. <<Pawn>>). They also cannot be used on NPCs which can talk; capturing speaking NPCs can be done in Elona+ with the Astral Light Pen.
Once a monster is captured, enter the Use (t) command on the ball and release the monster, which will then become your pet. Once you have released a monster from its ball, the ball is consumed. The released creature is not an exact copy of the creature you captured. Instead it is a freshly spawned one of that type. So if target's level was artificially boosted, extra levels will be lost after capture and certain details will be different, such as name (if any), randomized inventory, a shades mimicked abilities, etc.
Wishing[]
Wishing for monster ba will create a single monster ball. The spawned ball's level seems to be random, with your current level being an influence (ie. a level 30 character probably won't get a level 100 ball). Using a blessed or cursed Monster Ball doesn't affect the chance of capturing a monster, but cursed balls are generally weaker in terms of level.
Elona+[]
Monster balls will not be more than 10 levels higher than the lowest dungeon floor cleared. Opening a ball will cause the game to save.
There are two other methods of getting monster balls:
You can use a Pot of Fusion to combine a 4-dimensional mirror and any openable item into a monster ball. Requires the carpentry skill to be at level 20. Previously recipe required an api nut, a spellbook of 4-dimensional pocket and any container. Item limit is 140 and depends on your deepest dungeon floor cleared.
In the South Tyris town of Melkawn, in the underground gambling hall, <Lend> the Taker sells monster balls. Of course, you have to first complete the Main Quest before you can access him. Investing in his shop gives a greater selection of monster balls and higher level monster balls.
Omake[]
Monster balls will sometimes be available from souvenir shops.
The level of the monster being captured will be retained. However, a fresh copy of the monster will still be produced upon releasing the monster, generating new equipment and monster name.
Additionally, monsters ball cannot be used in the Void. The ability to capture monsters in the Void using balls is reintroduced in Omake overhaul, though through the usage of void balls.
What are Monster Balls?[]