Interdasting.
Q+ Q0
0 goaded Q into trying his hand at "testing lesser species" (in fact he was likely the person responsible for instilling this desire into Q in the first place), a task that Q took to with relish, albeit immature relish – he was responsible for a planet-wide shower of fruit on one of the main planets in the Tkon Empire. 0, however, had other plans for the Tkon; he began manipulating their culture, their technology, their entire way of life, all to his own ends, the end result being a massive civil war in the Tkon's home system between Tkon and an outer-system planet, Rzom. But even in the face of such unrelenting adversity, the Tkon fought back - and nearly won - so 0 pulled his trump card, and in an act of almost unparalleled sadism, caused their sun (which was in its last legs of life) to go supernova only seconds before it was to be replaced with a new, fresh sun (courtesy of an advanced transporter grid, one that present-Q advised Jean-Luc Picard to find before someone else did). This act alone demonstrated how different he was from Q; even when it meant that he might not win, Q always gave lesser lifeforms a chance at success. 0 simply changed the rules completely when it seemed like the Tkon Empire might triumph over him.
http://memory-alpha.wikia.com/wiki/Q_Continuum_characters