Hidden, the Rune-Cursed

You have no maximum hand size.
{2}{u/b}: Hidden, the Rune-Cursed becomes a copy
of any creature on the battlefield except its name
is Hidden, the Rune-Cursed, it's legendary in
addition to its other types, and it has this ability.
"The best way to stay safe is to stay hidden. The best
way to do that is to blend in."