Deepstriking wyches is very risky, the charge with the reroll has a 50% chance of failing. I think there are only two things working at competitive level with wyches :
- Red grief wyches in raider : turn 1 they disembark, get 3", move, advance, reroll, and charge
- Cursed Blade wyches in the webway : at least you are immune to moral and have +1 strength, combined with a drug you can hit at strength 5 and thus wound big targets on 5+
Also, only one shardnet is sufficient to get the trick, no need to run 3 as the damage output won't make a big difference