Beautiful Strike (Su): At 15th level, once per day when the order of the songbird samurai confirms a critical hit against the target of her challenge, she can declare it a beautiful strike without spending an action. The damage dealt by the attack becomes nonlethal damage, and the target must succeed at a Will save (DC = 10 + half the samurai’s class level + her Charisma modifier) or be charmed as per charm monster (caster level equals the samurai’s class level)
Once per day
VS challenged enemy
Only on a crit
Save
4 level spell
Any ideas on how to improve it or change it out for a different ability?
Cha will probably be 2-6 points lower than a dedicated caster. os the dc is 1-3 lower than a regular caster of the spell.
But this gets mitigated by having the DC scale with level.
10 + 1/2level + cha mod is better than 10 + 4 + cha when you get this ability. But you would probably not get feats or anything to improve the save.
The DC is not the thing I dislike.
In the best case scenario, I'm using an 18-20 crit weapon with improved critical. Then I have a 15-20 crit chance 30%
So if I when to use this ability against someone I would need to make 4 attack rolls against that target before I have a 75% chance of making it. Then they have a save and let's say they need to roll a 16 and above to make the save.
With 4 attacks against the same target and a roll 16 or above to make the save. I have a 56% chance of using my ability against a target.
it's would be a lot easier for a caster to just spend a standard action and a spell slot to have one saving to overcome.
For the chance to be the same the caster needs to have a DC that's 4 lower and if the caster fails he can just retry next turn.