It might be required to import the class to avoid errors.
import crafttweaker.world.IExplosion;

To create an IExplosion object, you must obtain it from an IWorld and call it with any of these three methods:

• world.createExplosion(IEntity, double, double, double, float, bool, bool);
• world.performExplosion(IEntity, double, double, double, float, bool, bool);
• world.performExplosion(IExplosion);

ZenGetter	ZenSetter	Tipo	Descrizione
ZenGetter world	ZenSetter ​	Tipo IWorld	Descrizione The world of the explosion.
ZenGetter placedBy	ZenSetter ​	Tipo IEntityLivingBase	Descrizione The entity that initiated the explosion. If the explosion was caused by TNT, the entity is the entity that placed down the TNT, if applicable. Can be null.
ZenGetter position	ZenSetter ​	Tipo Position3f	Descrizione The position of the explosion.
ZenGetter affectedBlockPositions	ZenSetter affectedBlockPositions	Tipo IBlockPos[ ]	Descrizione A list of block positions that the explosion affects. May be null/empty before doExplosionA() is called.
ZenGetter playerKnockbackMap	ZenSetter ​	Tipo IVector3d[IPlayer]	Descrizione A map of players in the explosion area mapped to their respective knockbacks taken from the explosion.

• clearAffectedBlockPositions() - clears the list of affected block positions
• onExplosionStart(IWorld world) - returns a bool that is the result of the ExplosionStart event in the specified world, so this should be called if you want to use logic to possibly cancel your explosion before detonating it manually.
• doExplosionA() - performs the first part of the explosion; this includes entity damage, entity knockback, and affectedBlockPositions assignment.
• doExplosionB(bool spawnParticles) - performs the second part of the explosion; this includes sounds, particles, block destruction/dropping, and fire creation.