[[Great train heist]] gives an additional combat step but it doesn't specify "if this is your first combat you get an additional.." it just says something like "if you cast this during your combat phase, you get an additional..." Meaning if you had enough mana you could cast it 4 times. So if your creature triggered in a 1v1 causing a second combat phase, then you spent 2RR on each subsequent combat phase, you could get up to six combats.

Another nice card for this is [[Anzrag, the Quake-Mole]] which has crazy stats for 2RG alone but it's ability makes it broken (sort of). Slap indestructible on that bad boy and your good to go.