I think the different is that the others are Activated abilities, and abilities are instant "speed", while Thada Adel is just letting you play that card from exile, as if you owned it.
Oh, okay. That makes sense. I must have glossed over the fact that Thada Adel's ability was triggered and does not let you cast the spell on resolution of trigger, but merely gives you permission to use it.
Recently my friends and I were wondering about the timing restrictions about cards played via Hideaway lands (Mosswort Bridge et al). From what I understand via reading around on these forums and the wiki is that the ability allows you to skirt timing restrictions, i.e. playing creatures and sorceries on opponents' turns. It sounds like Horde of Notions is the same way, allowing you to play that spell at any time. However, the Gatherer text on Thada Adel, Acquisitor specifically mentions that you can't avoid the normal timing restrictions ("The exiled card is played using the normal timing rules for an artifact, as well as any other applicable restrictions. For example, you can't play the card during your combat phase unless it has flash. Similarly, if the exiled card is an artifact land, you can't play it if you've already played a land that turn. If it's a nonland card, you'll have to pay its mana cost. The only thing that's different is you're playing it from the exile zone."). What is the difference?
There's not too many in those colors, if you want artifacts/enchantments. These are the search requirements I used (ruling: "deals" "damage to" "target creature", Enchantments and Artifacts).
So the ones I've found: Psionic Gift, Lavamancer's Skill, Power of Fire, Krovikan Plague, Hypervolt Grasp, Hermetic Study, Dizzying Gaze, and Arcane Teachings. These are the permanent options I can find, but you can play around with the search options using these parameters.
If you just want creatures there are a lot more (my favorite is Vampiric Dragon).
Oh, okay. That makes sense. I must have glossed over the fact that Thada Adel's ability was triggered and does not let you cast the spell on resolution of trigger, but merely gives you permission to use it.
Kaervek's Torch, Disintegrate
http://magiccards.info/query?q=o%3A%22deals%22+o%3A%22damage+to%22+o%3A%22target+creature%22+c%21ubr+%28t%3A%22artifact%22+or+t%3A%22enchantment+aura%22+or+t%3A%22legendary+enchantment+aura%22+or+t%3A%22enchant+creature%22+or+t%3A%22tribal+artifact%22+or+t%3A%22tribal+enchantment%22%29&v=card&s=cname
So the ones I've found: Psionic Gift, Lavamancer's Skill, Power of Fire, Krovikan Plague, Hypervolt Grasp, Hermetic Study, Dizzying Gaze, and Arcane Teachings. These are the permanent options I can find, but you can play around with the search options using these parameters.
If you just want creatures there are a lot more (my favorite is Vampiric Dragon).