So I've been testing this skill recently and I've come to realize that this is basically a staff+dagger skill for magic assassin's. Why? Well, the damage of this skill is abysmal for its MP cost and does not provide any beneficial effects outside boosting ampr. Because this skill basically eats all your MP and no one else besides staff can instantly recover all MP in this instance, it is very useful for staff to use this skill. But there is a problem, staff, if built for magic attack, have very low ATK (1.5k at base? At lv205), and at the same time, low crit damage. This means you need gear such that it boosts INT (Gain +ATK from this too), MATK, CRT and CDMG. Not so much CSPD. Now why not 1h sword, knux, BG or Halberd? Proration. Yes arcane strike has a stupid high multiplier but only magic assassin's can really use it because; 1) You need to find a way to quickly restore MP afterwards to either reuse the arcane combo or quickly bust a high damage combo. 2) It's multiplier needs high MP, which is only provided by a way to maintain as such. Decoy attack can recover MP swiftly but at the same time, this brings another problem... 3) It is a physical skill. All the other physical weapons have no need to take this skill beyond lv1 for use as a save tag combo ender to boost AMPR. Magic assassin's however can use the skill or even spam it after spamming magic attacks. Well, even with all that, the skill is still very lack luster due to lacking anything else besides a high multiplier.