Kalizaar's advice contains a fatal flaw.
The password examples are of low entropy, and thus very easily guessable. If one is discovered (say, Blizzard gets their password database leaked, oh wait that happened last month) then it's very easy for an attacker to substitute GW2, Guildwars2, GuildWars2, etc, programmatically, for Diablo3. If you're going to use a passphrase, use Diceware (or another, similarly random method) and use DIFFERENT passwords for different games. The name of the game changing doesn't make it sufficiently different.
Let's pretend you used "SillyOysterDiablo3GamePuppies" as your D3 password. Blizzard converts all characters to upper case, so "SILLYOYSTERDIABLO3GAMEPUPPIES". IIRC they use SHA256. So the hashed passphrase is "c8645c8e57a38f00c2529bb722dc6e209b0ffbcb044ddf1bf00cf25c8c30c878". It took about 45 minutes to crack using a Core i7 930 and an ATI Radeon 5850 GPU, with the G8, Known passwords, and PC games list dictionaries, in oclHashcat-plus in hybrid mode. "an eternity" is a bit of an exaggeration.