Flame Ground and Pole of Agony are scroll that can be sold at level 1 (level 5 is 12,5k each, buying JP+HK won’t be so easy) and still be useful.
For players who already have the FG and PoA skills, you already have the attributes, so you’d be paying 1~2,5k (depending on how expensive are level 1 attack scrolls) silver for each double FG, or having some weak-ish AoE for classes that don’t have the attribute. Still it should be possible for rich parties spam 1 FG scroll each and have a great ET DPS increase.
For Warlocks, if those scrolls are 30s cooldown it’s the best that could happen to Pole of Agony. You don’t have to put a single point into it, just get the attributes and you have a 30 seconds CD Pole of Agony with attributes and more points for other skills.
It would also help a lot full support cleric builds to level with Flame Ground or Pole of Agony to be honest.