Some of your Brood mothers are returning to the fold, because they wish to rule the Swarm and they know that Kerrigan is getting stronger.
The terrans launched thousands of the devices at your broods on Char but is not a weapon
Heart of the Swarm - Infested Walkthrough
The main mission is destroy the Hybrid Lab.
One of your Broodmothers in the Koprulu Section is picking up a strange psinic signal. It is Zerg, but not part of the Swarm. Stukov will come to help you getting rid of the Hybrid.
Use your infestors to take control of powerful enemas. Thors, Battlecruisers and other terrain heavy ordnance make ideal target.
Note the infectors have more life while fungal have more damage. Use fungal growth on the marines to stop them from escaping.
- Neutralize Platform Defences
- Infest the Garrisons 
- Destroy the Dominion Outpost
- At least 1 infestor must survive
- Destroy the Lab Entrance
- Bonus Objectives: Creep Science Facilities 
Move your units to the left and destroy dominion forces. Then take the infestor to the marked location ahead by the Infected Garrison. You will be infesting and planting the virophage. Get your units along with infected virophage to infect the surrounding building.
Destroy the dominion forces and other enemies. Keep moving while destroying any enemy units coming your way.
When the infestors are out of energy, they can consume zerg units including the infested terrans to regain energy.
Use Parasitic Domination on the Dominion’s heavy ordnance. This will turn their weapons against them. Keep destroying Dominion outpost as you move around.
On the right locate the marked location/garrisons and move your infestors there to make virophage. Once eliminate the nearby enemies move to the infestors to the last marked area/garrison.
After a cut scene, you need to destroy the Lab Entrance, start building up units. Once you have enough units and once the gas is running out, move your units to the marked location (north-west of the map). As you move up a bit north you will come across a first wave of enemies, take them out and them move your units to the south-west of your base and destroy enemies there before they destroy the virophage.
Move your units alongside the infestors toward north-east and attack and kill all the enemies long the way. Finish off the wave of enemies and continue ahead. As you move toward the marked location keep looking for the garrison to move your infestors, you will have few minutes before the gas is released again.
As you moving you will notice three more location has been unveiled, you need to creep on all of these Science Facilities. Your creep will infesting the facility, you will need o do in all three felicities.
Also note the gas I recharging, guard your vorophages and get ready to be attacked. Take out the enemies near the middle science facility. Keep an eye on the vorophage in this area as the enemy will come back to attack again. Once the gas runs out, get your infestor to resume the attack.
Get more units to continue toward the marked location to destroy the lab Entrance. Make sure you have enough units before approaching the Lab entrance as it is heavily protected. When the gas runs out, is time to attack the entrance. Destroy the tanks long will everything in the area.
Once the area is free from enemies, head toward the Lab Entrance to complete the mission