Bane

Location
Bane is located in the sixth floor of the optional Crossbone Isle. Pretty much the entire room is a puzzle maze that must be fully solved in order to both exit it and get the Djinni, with the idea being to hound it to the elevated portion at the lower right of the room, then trap it with Halt just like you did to earn Kite back at Vale Cave. Refer here for the full walkthrough on Floor 6 of Crossbone Isle.

Description
When Set, it increases base HP by 12 and base Attack by 4.

When Bane's battle effect is used, the user attacks and a vaporous red cloud is let loose upon impact. It deals a Venus-based attack equal in power to the user's normal physical attack with an additional 60 damage points, and there is then a chance that the target will be afflicted with the Deadly Poison status condition. It is very similar to the Jupiter Djinni Wheeze, but with that being Jupiter-aligned and dealing 10 less bonus damage.

Ability analysis
In Golden Sun, Bane should theoretically be very valuable because of the very powerful and practical Deadly Poison effect it can trigger, making it one of only two possible options the party has to apply Deadly Poison (the other being the Unleash effect of the Wicked Mace). What blunts its usability is the fact that the endgame enemies it would have been greatest upon - Deadbeard, Saturos and Menardi, and the Fusion Dragon - are next to immune to the chance of status effects being applied onto them, and random monsters are typically dead in very few rounds of battle before the venom has a chance to kick in and be actually useful. As for pure damage, Flint outperforms Bane in that area on an endgame party. Perhaps the best chances for this Djinni to shine is when used against the mini-bosses of Crossbone Isle in the remaining floors, such as against the Cerebuses (the venom will do a rather astounding 440 or so damage at the end of each turn to a Cerebus). It also works effectively against the infinitely respawning Tempest Lizard of Suhalla Desert, as it is one of the few endgame bosses not completely immune to venom. This makes for a quick fight and high EXP.

In The Lost Age, when Isaac's party joins Felix's party along with their returning Djinn (granted that Password data transfer is in effect), Bane is essentially a slightly stronger Venus-element variation on the Jupiter Djinni Wheeze. Whenever the Venom effect kicks in, it is quite good depending on how much HP your enemy has, but the near-immunity of any boss-like enemy typically prevents that effect from happening from either of these Djinn.

Name Origin
Bane was a term used in the middle ages for poisonous plants, possibly why this Djinni is capable of poisoning its target.