Set the following constants to values that work with your quest.

ICICLE_BLANK_COMBO - Combo ID of any blank combo
ICICLE_RADIUS - Used to set the distance Link needs to be from the icicle before it falls
ICICLE_DELAY - The number of frames to wait before the icicle actually falls
ICICLE_HEIGHT - The Z height that the icicle spawns at
ICICLE_SPRITE - The sprite ID to be used for the falling icicle
ICICLE_IMPACT_SPRITE - The sprite ID to be used for the impact effect when the icicle hits the ground
ICICLE_SHARD_SPRITE - The sprite ID to be used for the ice shards when the icicle hits the ground
ICICLE_SHARD_STEP - The speed at which the shards will fly out from the shattered icicle
ICICLE_SHARD_RADIUS - How far the ice shards should travel
ICICLE_DROP_SOUND - SFX ID to use for when the icicle falls
ICICLE_BREAK_SOUND - SFX ID to use for when the icicle shatters

FFC Arguments:
D0: Amount of damage the FFC will do
D1: Falling speed of the icicle. Larger values will fall faster. Values of about 3-4 feel right to me.