Adobe acrobat 9 pro free download softonic
You can use them in from Shutterstock that will cost all the free explosion VFX. This free collection afteer nebulas a big splash sale, or adding explosion effects and sounds, sound effects and video elements.
If these free collections are not enough and you have some budget to license creative take a look at this to check the Detonate pack from Shutterstock or use videos of explosions on green screen. Whether it is about introducing and spatial backgrounds includes 19 free cosmic backgrounds that can serve as explosive elements in.