Unit-Order unit to cast spell

Alright this may be a noob question, but when I make an action that calls for a unit to use a spell on another unit or point, I can only use preset spells.(sorceress-polymorph, bloodmage-flamestrike, etc.) My question is:

How do i use this trigger to order a unit to cast a custom spell?

Any help would be greatly appreciated.

use the one, your spell is based on

Exactly what arohk said just for example if you made your spell off of for example Cluster Rockets then just select cluster rockets but if yours is a custom then just make your spell find it and select it. Simple really.

Just to confirm... modifying the order string in the spell editor doesn't do anything, does it?

Unless the spell you modified is channel, that can have bad side effects. I recommend that you do not screw around with the orderstrings (unless you want to make a auto-cast spell non-auto-cast in which case you cna remove the turn on/off string)

Ok WTF rtm2 really confused me, and for some reason i try to use the base spell as the preset, but nothing happens.
Ill just restate the question
On regular World Editor, you can only select preset melee spells when using the EVENT - UNIT - ORDER UNIT TO (SPELL HERE) UNIT.
("SPELL HERE" is like Blood Mage- Flamestrike). Now, I made a custom spell based off of flamestrike. It does NOT appear on that list. How do i order a unit to use that spell using triggers?

You order it to use Flamestrike, exactly as they said. Unit - Issue Order Targeting A Point is the action, not Targeting A Unit.

Order (unit) to (Blood Mage - Flame Strike) point.
Thats it... if your spell was based from Flame Strike, use flamestrike, your custom spell won't show up on the list but it has the same order string. Just make sure the unit casting the spell has enough mana to cast it.

To elaborate...

I think it was before the 1.17 patch, so this may have changed. I shift-clicked on the order string of an ability in the object editor and changed it to a non-standard value, from <summonwareagle> to <summonwardragon> :-)

Then I changed the order string for Summon Bear from <summongrizzly> to <summonwareagle>. I had the `grab order IDs' trigger, and I also set it up to issue `summonwareagle', `summongrizzly', AND `summonwardragon' a few seconds into the game.

Issuing the `summonwardragon' order had no effect. `summonwareagle' summoned a dragon, even tho I had changed the order string to ..dragon. `summongrizzly' did exactly that, even tho the order string had been changed to ...wareagle. And the order strings that came up were the default ones for the base ability, not the modified order strings... but then again, maybe that's just a result of how the ConvertOrderID2String native (or w/e) works...

Still, my conclusion was that changing the order string in the object editor doesn't do anything.

Thnx i got it working