re GP: "... the power of a queen on an open board." I offer the following; might be to the point. The position was recently reached here at RHP,
Game 10356957 (Black to move):
the game continued 35. ... Rb7; 36. Qe8, Rxb2; 37. Qxc6 upon which Black resigned.
A possible continuation might have been: ... Rxa2; 38. Qb5, Ra1+; 39. Kg2, a3; 40. Kh3, a2; 41. Qb2 whereupon Black can no longer hold the a-pawn, the R is forced to move away and will eventually be forked off by repeated Q checks. E.g.: 41. ... Rf1; 42. Qxa2+ Kb6; 43. Qb3+, Kc5; 44. Qc3+, Kb6; 45. Qb4+, Ka7; 46. Qa5+, Kb1 or Kb2; 47. Qb5+ wins the R.