FROM LEVEL 21
Yellow Burr.
A very bright warning.
A strategic EMP freezes exposed creatures for four seconds while Burrs move twice as fast. Two Yellow Burrs join the pond from Master.
Shake. Ring. Think fast.
The Yellow Burr waits for a useful chance to attack at least two exposed creatures, then shakes before releasing its yellow ring. Creatures roll their eyes while stunned. You can still loop them, and the round countdown pauses for the stun.
Put a line between them
A completed herding line protects creatures behind it. Rescue Pulse can interrupt the shake and shield creatures. Each Yellow Burr has two EMP charges per round and stays with active spikes after using them.
Two charges each. One shared clock.
Master and Legend allow two Yellow Burrs at once. They each have two charges, but their stuns do not stack and the speed boost stays at double, rather than multiplying again.