Например, можно сделать капли падающие из крана...
Медленно набухающие, а затем, через действие бомбы, резко падающие.
Время жизни (life time) или больше 10, время общей анимации (Stop Time) 12, grow 10, fade 0 или -1.
Выдержка из оригинальной справки. (NDL Gamebryo 1.1)
NiParticleGrowFade handles two effects: particle growth and fading. Particle growth occurs when a particle is first created, and causes the particle to grow into existence from nothing to full size over a specified period of time. Particle fading occurs when a particle dies, and causes the particle to fade out of existence from full size to nothing over a period of time. The two effects are independent, and if they overlap, the particle will be the smaller of the two conflicting sizes.
If the NiParticleSystemController is set to have particles spawn, only the first generation will experience the growth effect, and only the last generation will experience the fade effect.