Milling cards on entry opens up many deckbuilding options, especially when you build around mechanics like delve or escape
Its 4/2 body for 4 is about average considering its ability, and 3 mana to regenerate it lets you swing in every turn without fear of losing it
Overload [cost] means "You may choose to pay [cost] rather than pay this spell's mana cost" and "If you chose to pay this spell's overload cost, change its text by replacing all instances of the word 'target' with the word 'each.'" If you don't pay the overload cost of a spell with overload, that spell will have a single target
Depending on how many of these are gathered together, it can appear as a hound-like 10% Forme, the serpentine 50% Forme, and a Power-Rangers-style Complete Forme
I maintain two saved eBay searches for Magic cards: one for Alpha cards sold by ABUGames at auction, and the other for Beta cards from the same seller