"If you shove it in there fast enough, it shouldn't be any trouble," Strange hypothesizes, as he looks over at the tree again. Half a tree is still a really tall tree. But he's confident in his skills and confident in his magic that somehow they'll find a way to make this entirely dumb piece of showing off work.

"Of course, now I've found another problem. The way the magic works, the depth of the water shouldn't matter. After all, you're storing the tree in the reflection not the lake itself. But in order to get a large and stable enough reflection to do the trick, I suspect you'll have to get your feet wet."

While the lake doesn't really have tides, it does have various forest creatures who can lumber around and splash things and make it so the edges of the lake aren't as stable as they could be. Strange doesn't know what would happen if an item was only partially stored in a reflection and, truth be told, he doesn't really want to find out.