The round 3 violet scrolls or the yellow round 4 scrolls?

I personally prefer the violet one because it goes first. The yellow ones do give more buffs but it appears on round 4, which y that time "most" fights are already decided.

What do you guys think?

Also, I have two yellow scrolls and I 'am thinking of using them to upgrade my violet scroll. Is it a bad idea like I think it is?