Me and @mikeyjamez tested the ability for a sage sins tidal to block something we tested 3 100% spells 3 times for a total of 9 debuffs the first time 2 out of 3 went through the 2nd time 2 out of 3 went through but the last time it blocked all 3 against 100% debuffs
so averaged out this concludes on average that tidal is really roughly 55.555555% but not all things are 100% so in the end it evens out for tidal protections 66% evasion of debuffs,stuns,paralysis, etc..