Newb Bard question: When should I use the Mana, TP buffs?

[Elkya95]

Second question that I thought had been answered a while back, but second guessing - are SMN/SCHs Ruin/Ruin II affected by Foe's also? (I thought I saw someone say it did boost Ruin's damage, but that was a while back and I'm not aware of an element on Ruin... being that it's 'unaspected')

Foe reduces magic resist on the enemies, so ruins are affected.