CDotaBaseAbility:OnSpellStart in combination with
CDOTABaseNPC:SetCursorPosition are used to "Call" spells.
This is a powerful way to interact with Valve's spells in particular. This allows you to:
- Activate hidden abilities
- Ignore turn-restrictions
- Ignore castpoint or cooldown
- Ignore any other cruft associated with the formal spell-casting methods
This is easy to use, easy to configure and easy to think about. Here is an example that casts Tether on a hidden dummy unit, activated by a datadriven spell: