Spellthief line of items interaction with Damage-Over-Time effects.
Although this is kind of targeted towards Morgana due to her popularity, this applies to every champion that has a Damage over time effect.
While I think Spellthief line of items are in a great spot (high risk-high reward) there are some champions that are able to benefit from it more than others. Notably those that have Damage Over Time effects. The problem is currently, each damage tick procs Spellthief's bonus damage and gold generation. This makes it a lot easier for champions with DOTs to get gold than those that don't have since they only have to risk themselves once to apply their DOT effect, while someone else has to risk themselves "three times" as much to get all three procs.
Basically, make Spellthief only proc once per spell cast (per champion hit), not per damage tick.