Nobody knows where Vesper came from, only that she arrived with a deck of cards and left with everybody's tanks. She treats war as the grandest game of chance, and somehow the dice always seem to like her.
All of Vesper's units deal 5% less damage, so even trades go your way.
Vesper's rolls swing both ways: never leave a weakened unit in reach, because a high roll can finish it.
Every hit Vesper's units take fills their power meter, so strike hard in one turn instead of chipping away. When the meter is full, pull fragile units back.