The key card : Vairon prism
http://yugioh.wikia.com/wiki/Vairon_Prism
This is the msn chat between me and [yugi boy a.k.a cj]
from the screenshot, you can see that he says that vairon cube is a mistake by konami and activating an optional effect monster when synchro summoning will miss timing. nvm, go to next screenshot.
from the screenshot, you can see that he says that synchro does not have a chain but the summoning is the last thing to resolve so it's a chain that come out of no where.
This part is the best, he says that varion though is a tuner, it's best not used for synchro summoning but as a target for scrap dragon. so scrap dragon is well worth over $20 now?
In conclusion : i would like to seek help from forumers if he is correct or wrong? i believe he is wrong as i don't believe konami will make a tuner that have an effect that clashing with using it for a synchro summon.