deny isnt in lag of legends, so no you don't understand it really. they are heroes in dota, people will rage at you if you call them champions.
easiest to get into is ancient aparition and sand king really. their only job is to stun. when you're a support you're supposed to either buy chicken or wards at start and continue to buy them throughout the game. runes spawn at 0:00 so be there
what you should do is watch games being played(in the in game spectator mode) for a bit until you see who does what, then when you arent playing learn http://www.playdota.com/heroes
also: Warding is the most OP thing in the game, do it or lose
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