The 866 number makes sense if you look at ETHBTC chart.
There is a resistance level at 0.88.
Ethereum can be 0.88 BTC and BTC could hit $10,000.
This would give Ethereum at 888, close enough to 866.
Right now, Ethereum needs to convincingly go above that first white box to continue the rally, if it goes below, it will go back to the H&S direction.