ExMachina said:
I did, however, the GM's take is that the creature only gains the Int3 by virtue of the fiendish/celestial template. And since the template does not STATE that a language is gained at that point, the creature is unable to understand commands, and is just a dumb animal.
No, the summoned creature is a magical beast, not an animal. And the Intelligence gain grants the language; the template doesn't have to specify that it gains a language for it to do so. The test looks like this:
1. Does the creature have an Intelligence of 3 or higher?
2. If yes, then it speaks one language.
3. Does the text of the creature specify what language?
4. If yes, then it speaks that language.
5. If no, then it understands common.
By not specifying that the Intelligence 3 creature speaks a language, it understands common.
I will note that as a house rule in my campaign, templated summoned creatures do not understand common. They speak celestial, axiomatic, anarchic, infernal, or abyssal, whichever is appropriate.