a custom spell...

Im making a custom spell, based off of Blizzard. Instead of the shards that the normal blizzard uses, I want it to have dryads spears. How can I do that?

you cant because the SFX for blizzard is a shard moving down and the SFX for a drad spear is just a stick that doeant have any animtions, if you replace the shards witht he missile, then all you will have is drad missles just appearing there that will not move and disapear after a few seconds, if you want this then you have to get someone to make a custom modle

Or you can trigger it.. add a weather effect in the area if you want, and you can make dummy units at 1000 height (or 1500 for a good view) and order them to attack random enemy units in the area. If you just want the effect, you can order them to attack ground when giving them artillery weapon type.