At the beginning of your end step, each opponent loses life equal to the number of tapped creatures you control.
Throne of the God-Pharaohâ€™s ability triggers at the beginning of each of your end steps, even if you control no tapped creatures. The number of tapped creatures you control is checked as the ability resolves.
In a Two-Headed Giant game, the triggered ability of Throne of the God-Pharaoh causes the opposing team to lose life equal to twice the number of tapped creatures you control. Tapped creatures your teammate controls arenâ€™t counted.
If other abilities trigger at the beginning of your end step, first those controlled by your opponents resolve, then yours resolve. Each player orders their triggers in any order.