Help request for mixed damage masteries

I am trying to put down all the various masteries pages for the different kind of champs I previously created, and even though I have found quite some trouble for various categoires because some choices are really binding and overwhelming - and not because of keystones or one-point masteries excluding each other, but because of the overall dynamic of points distribution that has really changed with the reductions of overall options and points to put on a single tree -, more or less I think I have found a starting set-up to eventually adjust for various categories...

....

...except one, the mixed damage one

The offensive options for those champs are really split toward the end of both Ferocity and Cunning tree, so i can't really decide where to put the final 6 points (tier 5 + keystone points)

I'm really undecided between the combo of Battering Blows/Piercing Thoughts + Deathfire Touch from Ferocity tree (the former offensive tree), and Precision + Thunderlord's Decree from cunning tree (the former utility tree)

Because, as mixed damage dealer probably don't have enough gold/slots to build penetration(s), probably Precision is better as tier 5 mastery than the Battering Blows/Piercing Thoughts combo, but Deathfire Toutch is far more powerful than Thunderlord's Decree. It is also true, though, that the latter one is triggered not only by abilities, but also by basic attacks...but it has a 30 sec CD while Deathfire Touch does have not, and does not need to go through the three stack mechanism so it could be more ready for quick skirmishes/unexpected engages

So I'm really uncertain about which way to got, what do you think is better?