Karlach, Ticking Timebomb

Choose a background.
Vigilance, First Strike and starting Intensity 1.
Whenever Karlach deals combat damage to an opponent or you create a treasure token Karlach
gains 1 Intensity.
{t} Remove 1 Intensity, Karlach deals 1 damage to
any target.
{t} 3 Intensity, each player creates 2 treasures.
{t} 5 Intensity, deal 5 damage to all creatures.