For example, if you start the turn at 10 life, then gain 5 life, and then lose 7 life, you'll distribute five +1/+1 counters, even though your life total is now lower than it was at the beginning of the turn
Teysa works better with some cards than others and being a touch on the luxury / win-more side of things you do have to be a little careful with her
Its commons are particularly standout, as even after the top three above you have strong cards like Emergency Weld, Carrion Locust, and Ravenous Gigamole among others
Sanctum Prelate is a 2/2 Human Cleric that costs one generic and two White mana to cast
This is easier to help accumulate poison counters than attacking for infect damage with the potential of your opponent blocking your attack with a creature they control
Lyra makes sure that happens, giving them a power boost and the coveted lifelink ability