Bubble

Bubble is a status effect introduced in Final Fantasy XII and is also the name of the Arcane Magick spell which causes said effect. It has also appeared in the DS version of Final Fantasy IV.

Final Fantasy IV
Bubble appears in the DS version of Final Fantasy IV and it is accessible either through Tellah's Recall ability or through the Twin Magic command. It doubles the entire party's maximum HP.

Final Fantasy XII

 * "The character brims with life, doubling max HP. The effect is temporary."

Bubble is both a status effect and the Arcane Magick spell that causes it. Bubble doubles the Maximum HP of the character it is cast upon. Unlike similar abilities from previous games (the Berserker Howl in Final Fantasy X-2, for example) it also raises the current HP to reflect the new maximum limit. As an added effect, characters in Bubble status will be immune to Disease.

The License for the spell is Arcane Magick 5 and costs 60LP to purchase. The spell itself can be bought from the Clan Provisioner in the Muthru Bazaar at Rabanastre after attaining a Clan Rank of Ward of Justice.

Bubble Belts can be equipped to induce a permanent Bubble state. These can also be bought from the Clan Provisioner after achieving the rank of Headhunter. One will also become available through the Bazaar.

In the International Zodiac Job System version, Bubble is listed as Green Magick 3 License. Only the four Mage jobs, White, Red, Time and Black Mages, can cast it.