Jack-o-lantern acts somewhat like a grenade and shrapnel at the same time. A glowing jack-o-lantern is shot and it will bounce around, leaving behind some fire at times. When it comes to a rest, it will explode, dealing damage. Seeds will also pop out, which deal additional damage.
Similar to jack-o-lantern, but barfs out a volley of seeds sometime before exploding. When it vomits its seeds, the pumpkin's horizontal velocity will be reduced.
Similar to Shrapnel and Shredders, when the Jack-o-Lantern and Jack-o-Vomit is placed at the bottom of the map, almost all projectiles released will collide with the indestructible ground layer. This causes heavy damage to enemy tanks.
Firing Jack-o-Lantern at the three-quarters mark between you and your destination on flatland at a high angle will allow you to land this right on the destination. (If you have the 100 power angle just lower your power to 86 or 87. This method is most effective when using an angle above 40 degrees and you are approximately the same elevation with your enemy.)