Blue and black offer sweet interaction in the forms of efficient counterspells and removal and white brings great protection, more lifegain sources, and lifegain triggers to help you pull ahead
I like to run two in a Mono-White Aggro deck to give me some game-ending power
There is a turn 2 win, but it requires a very nutty draw (T1 swamp, on EOT Entomb your Protean Hulk, drop Ancient Tomb on turn 2, and then on your own EOT drop Necromancy to win...you can also do it in response to someone doing something to your hulk in your graveyard) Ok, so what do you actually do with this deck
These final six are ones that are firmly in the treat-yo-self category
Building a deck with a specific theme or strategy is arguably the most crucial aspect of MtG
That kind of simplicity and big beefy stats is always welcome