|The first thing that came to mind.|
Saturday, July 2, 2016
Druidic Ability: Binding Shot
First off, we obviously take the Binding advantage as a starting point. I'm going to consider Based on Bow skill an enhancement, but using the range properties of a bow as a feature. Requiring a bow is a small accessibility. This creates a pretty simple advantage but an interesting power nonetheless that looks like this:
Weak Binding Shot (-5%): Binding 10 (Druidic, -10%; Accessibility, Requires Bow, -10%; Based On Bow Skill, +20%; Costs Fatigue, 1, -5%; Feature, uses bow range instead of innate range) 
And a stronger version:
Strong Binding Shot (-5%): Binding 20 (Druidic, -10%; Accessibility, Requires Bow, -10%; Based On Bow Skill, +20%; Costs Fatigue, 1, -5%; Feature, uses bow range instead of innate range) 
So that is the ability spelled out as an advantage... to take it one interesting step further, to create a one use version of these using the Sorcery enchantment mechanics. We will take off the costs fatigue multiplier turning the costs to 20 and 40 respectively. That makes an EP of 2.4 and 4.8 respectively. This gives us about $750 for one of the weaker arrows (rounding for a nice number) and $1,500 for the stronger arrows. These numbers give me an icky feeling of being prohibitively expensive, so I'll go a step further and divide the costs by 5, making them $150 and $300 respectively. As a sundry item in a Dungeon Fantasy setting, this somehow feels about right.
Of course, if you want to learn this as an advantage, you could probably have as many/few levels as you like. Each level would be 1.9 points, which gives you a teeny break every 10 levels. Dollars to doughnuts, Imbuements also has this type of ability somewhere (p. 11, in fact,) but I do prefer advantages, so that is that.