Insidious
From D20advanced
| INSIDIOUS | +1 Modifier |
|---|
This modifier is similar to the Subtle FX feat, except Insidious makes the result of an FX harder to detect rather than the FX itself. For example, a target suffering from Insidious Damage isn’t even aware he’s been damaged, someone affected by an Insidious Drain feels fine until some deficiency becomes obvious, and so forth. A target of an Insidious FX may remain unaware of any danger until it’s too late!
An Insidious FX is detectable either by a DC 20 skill check (usually Perception, although skills like Knowledge, or Science may apply in other cases as the GM sees fit) or a particular unusual sense, such as an Insidious magical FX noticeable by detect magic or magical awareness.
Note that Insidious does not make the FX itself harder to notice; apply the Subtle FX feat for that. So it is possible for an active Insidious FX to be noticeable: the target can perceive the FX, but not its results: for example, the FX appears “harmless” or doesn’t seem to “do anything” since the target cannot detect the results.

