A 2/3 with deathtouch is a great body on defense, but if you get to attack with it, youll be able to set up your best possible draw for the next turn and easily trade with anything your opponent blocks with
Red decks need their removal to be able to go directly to the face, which is the one thing you cannot Terminate, and while being cheap is nice, the creatures you need Terminate for don't come out fast enough to reward you much for it being so cheap
While a 5/5 indestructible beater sounds like a reasonable threat at first glance, considering that Historic will likely heavily feature Teferi, Hero of Dominaria, Teferi, Time Raveler, and Oko, Thief of Crownsall of which incidentally answer a 5/5 indestructible Darksteel ReactorI'm not sure the plan will actually be competitive
Tawnos's Coffin ($118) You might note a few similarities between Tawnos's Coffin and Oubliette, and youd be right