Rikki-Tikki-Tavi tricks both snakes, Nag and Nagaina, so that he has the advantage when killing them.
Rikki tricks Nag by waiting in the house while Nag hides in the bathroom, so that he will be able to bite him in the right place and kill him without being in as much danger.
"Now, if I kill him here, Nagaina will know; and if I fight him on the open floor, the odds are in his favour. What am I to do?'' said Rikki-tikki-tavi.
Rikki-Tikki-Tavi tricks Nagaina by killing all of her eggs and running off with the last one so she will have to follow him.
Rikki-tikki put his paws one on each side of the egg, and his eyes were blood-red. ``What price for a snake's egg? For a young cobra? For a young king-cobra? For the last -- the very last of the brood? The ants are eating all the others down by the melon-bed.''
Rikki-Tikki gets Nagaina mad, so she is not thinking clearly, and she does what he wants her to do so that he has the advantage. It does not work quite as he expects, and he has to follow her down the hole, but he emerges triumphant.