Fire grenade
Primary purpose - Area denial
Secondary purpose - Offensive weapon
When thrown on the ground it create a pool of flaming liquid that damages players passing through.
When thrown above a doorway it creates a curtain of dripping flames that damages players passing through.
When thrown directly at a player it ignites him and will kill him in 1.5 seconds unless he crouches in water.
Ice grenade
Primary purpose - Path modification
Secondary purpose - Defensive weapon
Ice grenades temporarily freeze water when thrown in.
Deep water, the kind that kills you if you fall in, will freeze on the surface. Walking across is possible but if the ice is damaged in any way it will crack sending anyone on it into the lethal water.
Knee deep water, like the puddles on Hemmorhage, will freeze trapping any player caught within. They can still fire, melee and throw grenades but cannot walk or turn more than 90 degrees left or right.
A fountain, where the water falls in a parabolic arc from high ground to low ground, becomes an ice ramp that can be walked up when frozen.
If an enemy is hit directly he will freeze into a block of ice that cannot fire, melee, throw grenades, move or aim. The enemy is alive and unharmed while frozen. A frozen enemy can be used as cover forcing his team mates to either destroy him or shoot around him. A frozen enemy can be shattered in one melee or grenade. The enemy will eventually thaw out, regaining the ability to aim, fire, throw grenades and melee after 7 seconds and the ability to move after 10 seconds.
Both the fire and ice effects last for 10 seconds in all scenarios.