| zza ni |
it depend on the buff used.
master summoner gain the feat Augment Summoning at 2nd level. that feat already give all of his summoned creatures (that are summoned via a summon spell, his eidolon probably do not count) "+4 enhancement bonus to Strength and Constitution" which is the same kind of bonus bull's strength and bear's endurance give. so these specific spells won't stack with the summoned creature own buff from the feat.
so the answer is:
- YES the summoned creatures can be buffed, but depend on what buff is used, it might not have any added effect.
| zza ni |
it's most likely a misunderstanding.
he probably read that 'master summoner' can't (or more accurately shouldn't try to) cast bull's strength or bear's endurance on his summoned creatures
-as it won't stack with his augment summoning feat (they give the same bonus, see my post above).
it's not a matter with every summoned creature, it's a matter of 2 specific spells (the 2 above, or anything else that give the same or lesser bonus) and creatures that are summoned by some1 with said feat.
and it's not a question of being able to, it's a matter of not having anything added by casting them. (before casting bull's strength\bear's endurance the creature had +4 enhancement to his str and con, the same after)