If you have a block value of 50 and a mob hits you for on a normal hit, then when you block the attack it will only hit for Indomitable is not bad , but it will only ever be used in situations where the raw health is needed to survive.

This type of ability is not very common at all, some examples are Maul druid , Mind Blast priest. Diablo III.

Frostwolf Orcs. Isle of Thunder. Get an addon such as Quartz to help if you have latency problems, practice on some Blasted Lands mobs for Slam timing.