The Sun Grenade, also commonly referred to as the Sunlight Grenade, is an item and weapon added by Witchery. It can be obtained by using a Sun Collector with a Quartz Sphere and a Daylight Sensor and waiting through mid-day for the spheres to be charged. The Sphere can be removed by right-clicking on it.
A Sun Grenade can be thrown, and will cause nearby undead and vampires to be burnt, and, when they explode, possibly given blindness for about 10 seconds. A vampire can do this to themselves 10 times in order to level themselves up to a level 5 vampire. They will only level up if they are given blindness.
The Sun Grenade will not damage any blocks when it explodes, and will drop a Quartz Sphere.