Ash is a chainsaw from the "Mega Super God Pack" gamepass. It is one of the most powerful chainsaws in the game. Not because it gives a lot of trimmings, but because of a special move and handle-based item breaking that make it one of the best items for PvP.
Ash is an item in the aptly named Mega Super God Pack, which provides the player with an assortment of very powerful items. The gamepass (as of when this was written) costs 5,000 robux. However, the description states that as more items are added to it, the gamepass will become more expensive, sometimes increasing by 500 robux in one day.
Ash does not give many trimmings, netting the player a mere 9,999,999 per object mowed. It also has no player point granting ability. However, it excels in PvP for many reasons. First of all, it can break handle-based objects such as hats and tools, meaning you can disarm your opponents with a swift strike.
The real power of Ash is the on-click special attack. When used, the player is instantly teleported to the location specified by the mouse of the user. This can be a very devastating attack or an incredibly powerful mobility tool that trumps any walkspeed enhancer.
Ash and its mouse-over description are probably reference to the movie Evil Dead 3: Army of Darkness, a movie where the protagonist (named Ash) fights demons and undead with his chainsaw arm and shotgun. However, he could not use his chainsaw to teleport.