Bigby's Battering Gauntlet

You create a metal ram that modifies its size by fitting the object it is cast on.  It immediately starts attacking it, destroying any wooden with its first attack, stone with the second and metal with its fourth.
Arcane locks are dispeĺled on the first attack (wooden with an Arcane Lock therefore destroyed in two turns). Every other magical lock of higher quality has a 50% chance to withstand an attack.
The ram is an object, has AC 15 and hit points equal to half of your hit point maximum. If it drops to 0 hit points or the object is destroyed, the spell ends.