難問のスフィンクス/Vexing Sphinx

Creature - Sphinx
Flying <CR>
Cumulative upkeep-Discard a card. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) <CR>
When Vexing Sphinx is put into a graveyard from the battlefield, draw a card for each age counter on it.

Creature - Sphinx
Flying <CR>
Cumulative upkeep --- Discard a card. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) <CR>
When Vexing Sphinx dies, draw a card for each age counter on it.

Creature - Sphinx
Flying <CR>
Cumulative upkeep-Discard a card. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) <CR>
When Vexing Sphinx is put into a graveyard from play, draw a card for each age counter on it.

Creature - Sphinx
Flying <CR>
Cumulative upkeep-Discard a card. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) <CR>
When Vexing Sphinx is put into a graveyard from the battlefield, draw a card for each age counter on it.