In Warsh which surahs do you have to do taqleel whether you read madd badal with 2/4/6 counts.

Question
In warsh which surahs do you have to do taqleel whether you read madd badal with 2/4/6 counts and in other surahs you have option when reading madd badal with 4 or 6 counts.

Answer
There are 10 surahs in which the aayaat ending with an alif which is originally  from a ya' () is recited with only taqleel, with no other option, as long as there is not a ha alif attached to .  These suwar are:
 
When there is is other places besides the last word of the aayah in these same suwar, or in any other surah whether it is the last word of the aayah or in the middle of the aayah, then there is a relation between how long we lengthen medd al-badl and whether we read with  taqleel or no taqleel.  If we are lengthening , two counts, then we read an alif which is with a fath only (no taqleel). If we lengthen then we read an alif which is with taqleel only.  If we lengthen six vowel counts then we can read the aliffat which are either with no taqleel or with taqleel. 
There are exceptions to this as there are some combinations or words in which we read the alif with taqleel with no other option.  
For full details, please read the section on taqleel and imaalah rules for Warsh:
http://www.abouttajweed.com/warsh/lesson-nine.html