Decorate and add a miniature tree on top and wrap tiny boxes like presents for underneath.
you could put a christmassy plant on it like a poinsettia and put bobbles or acorns around it
Or add different height candles and add fresh or faux greenery and tiny ornaments.
Add ribbon and put candles with pine cones where the cake would sit.
Wrap up miniature boxes (cosmetics are a good source) and pile high on the cake stand. Hot glue individual boxes to hold in place. Wind fairy lights with clear wires around the boxes. If using battery operated, be sure to use rechargeable batteries.