I'm trying to create a weather spell for my druid (hail storm) and would like it to actually behave like a storm. The goal is to have randomly falling hailstones around the character that can hit enemies.

It seems that damage shapes will not be of any use as they are at specific locations. I thought about having an invisible pet to cast spells, but then the hail stones would always target units, but I want it to be random.

I tried to do it via missiles, and was somewhat close. By using gravity and almost a 0 velocity and a high position, I could get the particles to look good. Then I used a unit spawner with a great radius to randomly create the missiles. The problem I had was that the missile goes a certain distance and then dies. I could not get it to destruct upon hitting the ground. In the EVENT_MISSILEDIE I tried casting another spell that did a damage shape (like the embermage firebomb), but I found the particles did not line up with the damage. By turning on debug damage shapes, I saw that the damage shapes were all over the place, some oriented vertically, not on the ground!

Doing some debugging I think it is because the missile wants to travel a certain 2D distance and then die. I tried loading the MEDIA/MISSILES/MONSTERS/BOSS_STURM/BOSS_SHOT_FORWARD.LAYOUT (the only core missile I could fine with gravity) and found that if the max distance was increased, the "DIE" particle was rendered way beyond where the missile hit the ground. My conclusion was that the DIE event is not in the correct location when gravity causes the missile to collide with the ground.

I may just give up on this idea as it is my only spell that acts this way (I want to do a thunderstorm spell, but that would be easy since the lightning can target units and not miss). I'm curious though if anyone knows how I may get this to work so that the missile "detonates" when it hits the ground just by falling?

Thanks for any tips or suggestions.

That sounds SO COOL Andrew! Any chance to see a video of it in action?

I thought there was a missile property called 'Collide with World' or something like that which would make the falling missiles die when they hit the ground.  Not that you want to produce 2 different versions of the skill... but I believe the first option you tried out should be doable.

Good luck!  This sounds nice.

oh hay guys , long time no see
anyway.

i feel like i gotta chime in here, since ive made a skill in the past that i think does exactly what you want.
take a look and see if it fits your description
you should take cthons advice and model the particles based on meteor, (falling component + the delayed explosion), 

for the delayed explosion you'll have to set the particles to "orient and spawn on ground"
this causes the particles to always appear on the highest terrain.
Heres my skill to preview

now, a sub skill should be set up to cast on each event missile die, and you have particles which will play on its events, one thing to note is that the falling part of the particles has to be set to go off after you spawn a 0 duration invisible dummy unit (using its death or spawn events to create the particles), why? the falling particles behave oddly if you implement them manually, they will sort of stick to the terrain and fall from different angles,
example
i just recently found this out and fixed it while i was making the gifs for this post lol
this part is just being pendantic and you dont have to do it, but it makes the skill look nicer when you use it on uneven terrain or near walls
hope this helps and good luck with your modding.

Im really looking forward to seeing how this turns out as I am making my own version of a ranger class and druid and ranger spells are traditionally similar. Weather magic etc!

There are so many great ideas and incredible talent here.