Which spells have a "cast threat" associated with them?

Most of our non-damage debuff spells have extra threat upon cast. So, for example, if someone pulls a mob with an arrow and does 25 damage, if you cast CoS you'll pull aggro since CoS has a "cast threat" of more than 25 threat. Here's a list of spells and their cast threat:

None: 0 threat upon cast
Corruption
Curse of Agony
Unending Breath

Low: around 75 threat upon cast
Demon Armor
Detect Invisibility
Shadow Ward

High: around 115 threat upon cast
Curse of Doom
Curse of the Elements
Curse of Recklessness
Curse of Shadow
Curse of Tongues
Curse of Weakness
Siphon Life

As you can see, none of our DoTs have an associated cast threat, except for Siphon Life. Also, it seems that the threat can change based on rank. For example, Siphon Life (Rank 1) has a "low" cast threat (around 60 as opposed to 115 for Rank 2). Thanks to Pentjak for his intial tests on this subject.