Why is the mask unnecessary? I thought that and vlad stacked?
Vlads and MoM do stack (Valds give a Melee Life Steal Aura, while MoM gives a Life Steal on Hit Attack Modifier), but normally there are better uses of money then to stack life steal. At the very least, Vlads does give Doom the armor he desperately needs, so its not the worst.
What does 'deny a friendly unit' mean? So are the different classes (support, carry, etc.) 'hard' roles or just suggestions? I never pay attention to them atm, and basically play each different character in the same way. Is this completely wrong?
Denying is killing a friendly creep to reduce the amount of XP the enemy gets. When a friendly creep fall below 50% HP, you are allowed to start attacking it. If a person on your team kills it instead of an enemy unit, the enemy heroes gain less XP. Normally, you want to simply "last hit" your own creep to deny, but you can auto attack it to make it die sooner too, so the creep wave ends up closer to your tower.
The different classes are mostly a suggestion, but a lot of them are pretty accurate. Characters marked as support tend to still be able to do most of their damage without much money or even levels. Characters marked as carry tend to have abilities that scale with auto attack damage, and can make better use of money then most supports.
For example, a person like Faceless Void gets more out of items that grant attack speed due to his 25% bash chance then someone like Lich, who doesn't have any ability that benefits from additional attack speed or damage. Spectre gets more out of a large HP pool then Lich due to dispersion being a flat 22% damage reduction. Phantom Assassin get more out of attack damage then Lich due to her 4.5x times crit. Someone like Lich will benefit from items that give him sustain, mobility, or a larger mana pool, but doesn't need that much money to be effective, due to his spells dealing the bulk of his damage.
