Merlin's Mantle

Select a creature on your field; for 4 turns, while
said creature is on your field, said creature cannot attack, nor be attacked. If said card would be
attacked; if you control no other creatures, your opponent may attack you directly.
After a creature has been selected with the effect
of this card: once per duel, you may select a
creature on the field (except the one selected by
this card;) said creature's lvl is increased by 1 for
the remainder of this turn.