As the opposite to vitality, poisoned units take 1 damage at the start of their owner's turn, right before they advance. This damage will trigger elder abilities and can kill the unit if it is at 1 strength. Poison lasts until the unit dies, or is replaced with vitality.
Applying poison to a unit that is already vitalized will remove the vitality and give it poison in its place, and vice versa.
Visually, poisoned units have purple diamonds and yellow circle particles around them that surge when the poison deals damage.
Poison enemies to whittle down their health over time and make them vulnerable. However, many poison cards can also damage friendly units too.
Poison can be effective on both high and low-strength enemies, depending on what synergy cards you use.
Weaken enemy units with poison damage over multiple turns.
Use cards to damage and poison your own elders to force their effects to activate.
Remove vitality from enemy units and replace their strength gain with damage.