Goalkeeper (Must be player's natural position i.e. a GK) ** see note below
Some combination of at least 3 defenders (i.e. 3 players anywhere in the back row [DL, DC, DR] )
At least 1, but no more than 2, players on EACH outside flank. {the DL/DR, DML/DMR, ML/MR, AML/AMR slots}
at least 3 midfielders (DM*, M*, AM*) at least one of which has to be an DMC or MC
At least 4 players on the opponent's side of the pitch.
at least 1 Striker

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Seems legal to me.
It's somewhat similar to 4-1-4-1.
I believe the possible counters are 4-2-2-2 Hexagon and 4-5-1 V, given they have means of countering the formation. Both however, relies on the empty DMR slot for chance for victory. Any formation that attacks on flank while strong in middle and have flank defender should do I guess.