Eh? the spells are supposed to be measured purely in ticks, which just coincidentally are 6 seconds a part. it should be virtually impossible to cast it on the first tick and even if it did would just count it as a tick,leaving you with just 3 more to go. See this wiki
https://wiki.project1999.com/Vexing_Mordinia for a counter claim of getting less ticks than advertised. Something is fucky.