Since both are concentration spells, the caster becomes a priority target of any intelligent opponents so depending on the targets and initiative order the spell might not even give the modifier once.
In any game I ran, they'd have to be pretty intelligent. It's not like Bless or Bane creates an obvious in-game effect. I might see an opposing cleric maybe noticing or someone with super-tactical "Admiral Thrawn" type insight. It's like being made more or less lucky, not supercharged with glowing power.
Otherwise, I just feel like I'm using GM metagame knowledge that most GMs don't like players using.
IMHO any non animal intelligence level opponent could and should make an intelligence (arcana) check to know the function of a spell they can see being cast whether there is a visible effect or not.
If a caster waves his hands around and says magic words, you know something is up.
In any game I ran, they'd have to be pretty intelligent. It's not like Bless or Bane creates an obvious in-game effect. I might see an opposing cleric maybe noticing or someone with super-tactical "Admiral Thrawn" type insight. It's like being made more or less lucky, not supercharged with glowing power.
Otherwise, I just feel like I'm using GM metagame knowledge that most GMs don't like players using.
IMHO any non animal intelligence level opponent could and should make an intelligence (arcana) check to know the function of a spell they can see being cast whether there is a visible effect or not.
If a caster waves his hands around and says magic words, you know something is up.