The Master frowned as he witnessed the hidden bar. He thought the one on display held the good stuff but he could easily see the hidden one had much better stuff. Something else he had missed in his explorations. Did this Lex Luthor have some way of shielding things from the scanner function of his laser screwdriver? There was no two ways about it. As devious and ingenious as this Lex Luthor was turning out to be, The Master could spend months searching the building and still not find all the hidden goodies inside.
As for the sentry bots? The Master had faced cybermen and Daleks in his career. Those things were just not in the same league and he hardly gave them a second thought. Although he did take note of their weapons and mentally calculated possible escape avenues if things turned out badly.
Yes The Master was not overly worried about the new situation at all. However.... He also was very much alone at the moment in this strange world without allies or associates and the Doctor had at least several of his other incarnations plus numerous companions to turn to for support. The Master decidedly didn't like those odds. Tapping the laser screwdriver against his neck a few times as he pondered his options he finally settled for smiling and placing it back in his jacket pocket.
"As you say, I would make a strong ally and I already am familiar with the current situation while you are obviously fresh to the game, while you are intimately familiar with the layout of this building and all the toys that go with it." The Master said with a pointed look out the window at the hovering robots. "Let's discuss the situation, ally."
((I prefer to react to situations and follow other's leads rather than plot things out.))