Haven't mathed it out yet. But, shield charge/leap slam/chainhook are obvious options. Maybe vigilant strike/concpath.
CD is .724s with its 38% cd speed at 20, btw.
Its a SEPARATE extra hit. which might have value somewhere. Impale for example.
Ruthless is top teir dps in many skills as a support and its 132% more damage every 3rd hit.
Shockwave is clearly strong for clear, as its BURSTING frontloaded damage.
And an extra 210% of base damage hit is often over "100% more" damage.
1000 damage baseweapon damage leap slam. 1200 base leap slam+2100 shockwave for 3300 total.
Shield charge might be the REAL winner. does it shockwave mainhand or offhand shield? If its the mainhand weapon, you have might have some real interesting options.
So shockwave might replace ruthless or even multistrike. Especially with ani-cancel and dodge skills. dealing 400% weapon damage, dodge, 400% weapon damage, dodge. is a HELL of alot better then standing there for .75seconds to deal 475% multistrike damage, etc.