Hero was hammered. No, wait, hammering. Hero was hammering away like an inexplicable anime as he used his magic mallet with no fire to shape the tools they brought with them. Batman would never willingly let his tech fall into the wrong hands, so Hero had taken up the crates of titan toys with them to the new location where he was at work experimenting. 

Minimization is always something useful, smaller means easier to place or more to carry, since he could not affect an objects mass, he could affect its density. For the moment he was practicing with grenades to make them smaller and smaller by removing the gaps in the molecules to make a more 'solid' explosive that could fit more in the hand. After the grenades, he would look to experimenting on that talon costume they confiscated to see if any technology from the court of owls could be put to their use.

Now, before you ask, hes not so stupid as to be using explosives or even flash bangs in the hotel. He's practicing the technique with gas grenades only loaded with liquid mist as he tries to improve on not only his own limited skill with this tool but also improve the team as a whole in his own way. With headphones on, listening to greek music, he's blissfully unaware of the knocking on the door. 
[youtube]https://www.youtube.com/watch?v=Qoq7mRY1j-I[/youtube]