I swear, I created a monster with very, very similar mechanics to the Azure jelly (however he also had a recharging reaction that let him steal attacking weapons, too).
The sand golem has to be my favorite; I can just see that thing zipping around the battlefield. The shadow slime is brutal; that will make you afraid of the dark!
I really like how the iridescent ooze's alluring colors power synergizes with its ability to mark targets. IMO, it adds an interesting component to a soldier monster.