As odd as it may seem, the last episode of the second series - The Chosen One - has to go at the top of this list: Vampires are slain; the ineffectual monster hunter becomes a threat, Vlad accepts his destiny, and Ingrid threatens revenge on all of breather-dom. Damn this show got awesome fast.
The undiluted awesomeness happened even before The Chosen One. In Insomnia, we got the battle between Vlad and his own personal Grand High Vampire. They use sunlight as a weapon!
Ingrid taking control over her reflection and thus gaining control when merged
It may be easy to say that series two has a lot of awesome moments.
The first time we see Vlad's vampire powers when he goes to rescue Ingrid. Clearly he is not to be messed with now.
Evil Vlad is just a walking, talking crowning moment of awesome but nothing can compare to him talking Count Dracula into trusting him then trapping him and torturing him with garlic. The whole scene is made by the look on Vlad's face when his Dad is unchaining him and his cheery "See you!"
His treatment of Ingrid is also impressive - after she spends most of the episode whittling a stake, she charges at him using vampire speed. He stops the stake with one finger, and then throws her out into the sunlight. Really, Vlad must have at least some suppressed anger for the way his family treats him and his friends.
Vlad's plan to beat Sethius
What makes this so awesome? He planned to be found out and still come out with a win.
And he got slayers and vampires to agree to a truce, which everyone had spent the past three season (seven years!) telling him was impossible
The Count going full Papa Wolf during Vlad's wedding.
Leading to the Count versus Ramanga in the next episode.
The Count: Outnumbered, perhaps... but never outclassed.