Equipped creature gets +2/+2.
As long as equipped creature is legendary, it has hexproof. (It can’t be the target of spells or abilities your opponents control.)
Equip
It's possible for a Champion's Helm you control to be attached to a creature an opponent controls (if an opponent gains control of your equipped creature, for example). In this case, the creature couldn't be the target of spells or abilities you control, as you are an opponent of the controller of the creature with hexproof.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.