Upgrading the spell to level 2 will double its duration on the battlefield.
Make sure to always use the Jump Spell near Walls! If you accidentally use the Jump Spell elsewhere, it will have no effect, wasting the spell, your Elixir and your time.
This spell is more effective on doubled or tripled Walls; otherwise the spell is not utilized to its maximum capability, making it much less valuable to use.
The effects of the Jump Spell do not change if you drop more than one spell in the same area, so be careful not to use to in the same place!
Especially with the new Wall Breaker AI, Jump Spells can be quite useful for getting Troops deep into the interior of a base. Once Wall Breakers have initially breached the exterior Walls, any new ones tend to be attracted to adjacent cells rather than those behind the breach. A Jump Spell, however, can be placed behind the initial breach to quickly allow Ground Troops access to the second layer of the base where the storages and heavy defenses (Mortars, X-Bows, etc.) are typically positioned.
The level of the Wall does not matter to the Jump Spell; Troops will be able to jump over Walls of any level.
Jump Spells have no effect whatsoever on air units, as they already ignore Walls since they are flying. This also does not change the behaviour of Hog Riders or Wall Breakers in any way.
The rings that circulate around the illustration of the Jump Spell is to resemble the action when troops jump over Walls.
The spell acts like a better (albeit temporary and more expensive) Wall Breaker.
The update on 17 June 2013 changed the behavior of Jump Spell. Prior to the update, the level 1 Jump Spell only affected Troops that required 4 or less housing spaces (Barbarians, Archers, Goblins, Wizards), with the remainder requiring level 2 to jump Walls. As of 17 June 2013, all Troops are able to use a level 1 Jump Spell, with level 2 doubling the spell's duration.