The attack is 0 because the effect says that is a combination from the 2 monsters. Since you used just 1, the effect don't applies.
Pretty good imo. Uses original Attack tho afaik, tributed two 1800 fiends while yami was active, got 3800 attack of that (1600*2+ 200[from yami]). Didn't work on itself tho, used a Maju Garzett with about 4500 Attack and that new 1750 vanilla zombie and ended up with 1950 (1750+ 200[yami]). :/
That it is a fucking 2 tribute monster? When was the last time you saw a 2 tribute monster on a viable deck on this game? Daedalus doesn't count because most of the time it was brought out with Big Wave, Small Wave