

You aim to generate small advantages over the game that results in you being far ahead. If wood elves is good for 2 forests when you cast it, imagine getting a forest for casting and then sac'ing it with skullclamp for draw 2 cards only to be recast through ] or ] or ] and then recasting it for another forest. Often times, reanimator cards are creatures that can be easily recurred should they be destroyed or have multiple activations throughout the game. Grind reanimator is using creatures to generate advantage in card draw, lands, life, control, and damage through enter the battlefield/leaving the battlefield/sacrifice abilities. Your graveyard essentially becomes your second hand.

Dredge can be used to toolbox by letting you fill your graveyard with creatures and selectively casting them to best fit the situation. But both can be toolbox or grind decks also. These are both examples of combo dredge and combo reanimator. I'm gonna add a little something on this real quick.
