MtG Rules Advisor & Goth/Industrial/EBM/Indie/Alternative/80's-Wave DJ DJ Vortex
DCI Certified Rules Advisor from July 14, 2009 to July 14, 2012 DCI #5209514320
Wit found in Rules Q&A
RPJesus: "Man, screw the rules, I'll play a game of 2HG Archenemy Planechase Emperor EDH draft yet. Once I figure out the rules for it..." Chaikov: "Of course, casual Magic may be played any way your Pokemon group agrees on..." and "It's not logic. It's Magic!" GainsBanding: "I only play online. The Magic Online shuffler is AWESOME!" Ikegami: "one might think [adult cats] would make excellent tokens. The issue, though, is that they are very hard to exile. They return to the battlefield more often than an undying creature." Astarael7: "Does 121.1 imply that players are supposed to wear their poison counters?" Bimmerbot: "If you move the wrong way and [the poison counters] fall, it's a game rule violation" Helluminatus: "Just remember, if it looks like a duck, smells like a duck, and quacks like a duck, but the oracle text says creature - Bunny , then by god, it's a bunny." MadCow21: "Who are you and what have you done with the real Chaikov?"
If you want to "Attack", then you can either attack a player or a planeswalker; only you can make that decision. The player (or controller of planeswalker) can opt to use creatures to block your attacks. You can not "Attack" his creatures; but if he uses creatures to block, you will end up dealing combat damage to those creatures.
If you are using a spell or ability to Target, you can (depending on the spell/ability) Target either a creature or player or planeswalker. In general, your opponent has no control or influence on this. If you use Shock to target a player, that player cannot choose for the damage to instead apply to a creature or planeswalker. You can, however, redirect the damage from the player to a planeswalker if you so choose. If you use Shock to target a creature, your opponent can't just take the damage himself, nor can he have a different creature take the damage.
Please note: As with most things in Magic, there are spells, cards, abilities, etc that will modify the above. Sometimes drastically.