Just  put  an  accuracy  chest  on  him    328  acc  and  its  still  the  same.  20  turns  and  landed  both  debuffs  7  times      

Do  you  have  him  fully  booked?

Yes

Spider  15  -  Rhazin  should  have  no  problem  landing  debuffs.

Spider  16  -  Is  different story

Spider  16  is  Spirit  Affinity  which  will  mess  up  Rhazin  ability  to  land  debuffs  due  to  weak  hits

I  understand  that.  but  from  15   all  the  way  up  to  25  he  rarely  lands  both  debuffs.  with  328  acc  he  should  always  be  landing  both  debuffs 100%  of  the  time  except  when  its  week  affinity.  Hes  not

There  is  a  3%  chance  to  Resist  debuffs  no  matter  the  Accuracy.

Ok  i  understand  that.  but  3%  is  hardly  an  explanation  on  landing  less  than  half  the  buffs

Well he only does the a2 every 3 turns. So in 20 turns rhaz will only attempt the debuffs 7x. So he landed 100% of time.

Problem solved!

It will probably best to show a video of at least a continues 5 to 10 runs with Rhazin for us to investigate what is happening. 

I  dont  mean  20  turns.  sorry.  i  meant  20  times.  I  have  rhazin  archmage  septimus  coldheart  and  royal  guard.  If  he  lands  both  debuffs  from  the  start  ill  kill  the  spider  in  12  sexonds.    If  he  doesnt,  i  dont  get  the  kill.    So  thats  20  fresh  starts.