2d Effects Animation
This is a large portion of effects animations I've done for a top down shooter game for mobile development. All effects were done in flash, exported into a sprite sheet with Zoe (an Adobe Air, sprite organizer) and optimized in Photoshop.

Many of these effects are either projectiles or wave attacks done by the player as a stand alone animation.
However there's a few effects that are meant to be part of a particle generator and building blocks of more ornate effects. I have to say this is one of the most fun projects I've done, requiring grinding frame by frame flash animation with a foreknowledge of where you'd like the effect to go, given it's descriptor and in game behavior.

Designed to be stand alone attacks shot by the player, each having a particular behavior or pattern. These were certainly the easiest to create because I just had to make looping animations, some harder than others.
Impact Effects 

These were definitely the most fun to create, basically a series of effects that happen when certain abilities impact it's target. Due to the nature of these animations being the only ones occurring in "real time" as opposed to looping states, there was a lot of planning to insure they were timed right and created the correct effect. I spent a lot of time looking at 10'000 fps video footage to see how materials and fire react in an explosion so I could make the keys look as authentic as possible.
Shields and Emanating Effects

These are circular wave effects generated from the player outward or simply surround the player like a shield. In particular these were the most grueling animations, requiring many more frames, detailed effects and several animation states. The circular radiating effects in particular needed a generation, sustain and release animations, though I've simplified them for display.
Channeled Effects

Channeled effects are essentially a stream of sprites to create streams of water, flamethrowers and streams of lightning. Conceptually these were the most challenging to make because the huge amount of thinking needed to generate a looping sprite that when multiplied onscreen both looked convincing and homogenous so it wouldn't look so obviously like repeated patterns.

The Lightning and Fire effects also both needed death animations which are included here with the initial looping and generation effects.
Static and Secondary Effects

Earth effects were much less fluid and involved more sliding static images, the rock walls in particular were basically non-moving sprites that could shield your character. I've included them simply because I love the style of rock I made rather than how interesting the animation is.

Secondary effects were animations made for accompanying particles, like a smoke trail for the fire effects or additional electrical arcs that were generated off a projectile as it moved. These are just my particular favorites.