So by RAW, the following do not break invisibility, right?
- Blowing a horn to call reinforcements
- Blowing a horn of blasting to smite your foes
- Blowing a horn of blasting harmlessly into the air to call reinforcements
Those are all an "Action", not an "Attack (action)" (an attack action being, by RAW, a melee or ranged attack).
What about wands? A Wand of Binding lets you cast certain spells on command, or gain advantage on a roll. I assume you'd only pop out of invisibility if you use the Spells action and not the Assisted Escape action?
Also if it's house ruled that ability that triggers a save count as an attack, then yeah, that would cover stuff like beholder eye rays.