Endless swarm

The swarms of the Hydra are numberless. Kill one
organism, and two more will take its place.
Use this Stratagem at the end of your Movement
phase. Select a unit of Termagants, Hormagaunts
or Gargoyles (or any HYDRA INFANTRY unit)
from your army that has been completely
destroyed. Add an identical unit to your army,
and set it up as reinforcements wholly within 6"
of any board edge, more than 9" from enemy
models