Use the mana value of the sacrificed creature as it last existed on the battlefield to determine the value of X
However, its not just strength and willpower which determine what makes the most powerful Lorcana card, as the side effects listed below these stats are what can separate winners from losers
The folks over at Magic headquarters weren't being ignorant, they knew exactly what they were doing for the sake of the game, but still wanted to let us know they did their science homework by implementing it where they could
Its extremely easy for these commanders to come out ahead on this exchange and there are plenty of ways for them to use the cards that get discarded too
So far, that effect has not been very useful
Read More: Get yourself one of the best MTG Playmats 5 Shamanic Revelation This is another one that lets you draw cards and also gain life, but it costs five mana instead of four