Hexproof & Ward
Keyword abilities
Two different protections from being targeted — one blanket, one a tax.
How it works
Hexproof means this permanent can't be the target of spells or abilities your opponents control. You can still target your own hexproof permanents.
Ward N is different: it's a triggered ability. Whenever the permanent becomes the target of a spell or ability an opponent controls, that ability counters the spell/ability unless its controller pays the ward cost. The target is still legal — ward is a tax, not a wall.
Shroud, an older variant, means the permanent can't be targeted by anyone, including its own controller.
Common confusions
“Does hexproof stop a board wipe or an edict?”
No. Hexproof only stops targeting. 'Destroy all creatures,' 'each player sacrifices a creature,' and other non-targeted effects ignore it entirely.
“Can you pay ward and still have your spell countered another way?”
Paying ward stops the ward trigger. The spell can still be countered by other things, and ward triggers separately for each opponent's spell/ability that targets.
“Targeting your own hexproof creature.”
Allowed — hexproof only blocks opponents. (Shroud blocks everyone, including you.)