Unit went off my board

In the final round of the ranked game my Level 3 Lucian (Seraph, Ludens, Gunblade) just went off the board and stood next to the map, doing nothing. I placed him on the far left hexagon in the second row. I played with Lucian, lvl 2 Gnar, lvl 3 Braum, lvl 1 Miss Fortune, lvl 1 Kayle, lvl 2 Cho'Ghat, lvl 2 Leona against a Demon Comp in case that matters