This cheater took my rook with his queen, which is illegal because

Rules of Chess: Check, Mate, and Stalemate

Glossary of Chess Terms Kid Chess® Atlanta, Chess for Kids

Chess tactic - Wikipedia

CHAPTER 6 DOUBLE CHECKS INTRODUCTION Diagram 156 - Name the white pieces that can both check the King at the same time on white's next turn.

Double checkmate - Chess Forums

Concepts + Examples of Discovered and Double Checks - Full Chess

Champion Tactics with GM Wolff - Discovered Check & Double Check

DOUBLE CHECK, DISCOVERED CHECK, CHECKMATE, ALL AT ONCE

Putting a player in check from 2 angles at same time in one move

The Double Check Tactic