Just how easy is it to get Warp? The rules for living in auras and under continuous magical effects are better explained and don't require much adjudication.
Powerful mystical effects, however, are a whole other problem. Here's a list of what I think summarizes the more easily identifiable traits that would influence whether a spell inflicts Warp, and I'd like to hear your thoughts on which interpretation is the most appropriate under the RaW.* Past of Another, Twist of the Tongue, Cheating the Reaper, etc: These are the obvious candidates, and I highly doubt anyone would question whether they inflict Warp
Ball of Abyssal Flame, Incantation of Lightning, Enigma's Gift, etc: These spells are all magnitude 6+ and target an individual while having the Target be their effect created
Ward Against Faeries of the Wood, Ring of Warding Against Spirits, etc: It's explicit that these will Warp with constant exposure, but it's more questionable whether they Warp at first exposure when they're level 30+
Neptune's Wrath, Fog of Confusion, Breath of the Open Sky, etc: These are certainly powerful mystical effects, and they certainly 'affect' you if their Penetration is high enough; but the only thing that separates them from BoAF is that they don't have you as a 'target'. The big question is that were these to be extended in duration, would they bestow long-term Warp? If so, would there be a reason why they wouldn't Warp with short-term exposure?
Walking Corpse, Steed of Vengeance, etc: The only difference between these and Neptune's Wrath is that they are more 'dodgeable'. By the same token, if you ride a Steed of Vengeance long enough, would you pick up Warp? What if it's only a low magnitude effect, like a regular horse that's been turned blue?
Powerful Mystical Effect is anything of 6th magnitude (level 30) or higher.
Note that they warp the Target of the spell (note capital T). This means the spell must directly apply its magic to the target (lower-case t) for that target to be warped. If they only indirectly affect something, that something does not get warping.
Cheating the Reaper (CrCo) : absolutely! it's targeting someone with a high-level magical effect
Ball of Abyssmal Flame (CrIg) : No. It's Target is the created fire. The horrible burning sensation experienced by whatever is right where the incredibly hot fire is happens to be a side effect, not the spell effect itself.
Neptune's Wrath and Breath of the Open Sky are the same as BoAF - their devastating effects are side effects of the spell, not the direct application of magic.
Fog of Confusion, however, does directly affect the persons its targeting. So this does cause warping.
Steed of Vengeance is going to warp the horse.
Walking Corpse won't warp anything because it's too low magnitude (25). But if it did, it'd warp the corpse only.
Wards: Is it explicit? There's likely a difference in behaviour between a ring-ward and a direct-targeted ward, again due to Target/target.
The old Target/target confusion comes up far, far too often.
Target (capital T) is the thing which is being directly affected by the magic.
target (small t) is an entity whom the caster intends the final result to affect.
If I cast a spell to levitate a rock, move the rock over someone's head and then cancel the spell, the person whom I am levitating the rock over is my target; they are the one I intend to ultimately affect. However, I am never actually casting my spell at them - the Target of my spell is the rock.
For a Creo spell that creates a thing, the Target of the spell must be either individual or group. It cannot be anything else. This is because the Target of the spell is the thing or things being created. Thus the Target for Conjuring the Mystic Tower is the tower, the Target for Ball of Abysmal Flame is the ball of fire.
For a Rego spell the Target is the thing being directly controlled. For a spell like Ominous Levitation of the Weighty Stone this is the rock being levitated.
Both BoAF and Ominous Levitation also have an intended target: the entity that's going to take damage. While this entity is often referred to as the target of the spell, they are not the thing that the spell is affecting. The spell is affecting either the fire being created or the rock being levitated, not the person who is getting some serious pain as a result of the fire / rock.
Fog of Confusion has a Mentem component; it directly messes with the minds of people. This is why it warps; if you remove the mentem effect so it's just Fog of Impaired Visibility, then it wouldn't warp people.
Walking Corpse would warp the corpse only. There is no circumstance at all where it would warp anyone or anything else. Same deal as BoAF, Ominous Levitation and many, many other spells.