Haste vial is better than rocket spear

Haste vials allows you to avoid using another invisibility spell because RC isn't quick enough to destroy a building when you're otherwise using Rocket spear. So in some cases you'll have to use two spells in succession to just keep her alive and moving.

You're also less stuck slamming down on a high hp defensive building if you pop your haste vial as well.

I want to like rocket spear I really do but man it sucks in general it's just really good if you don't want to think about how to tunnel your RC straight into important defense. I get more building destruction percentage from Haste vial

Also bit of a off topic but is it worth maxing out King equipment instead of Minion prince?