Trinity Core- How to make a summoned mob heal a boss

[Scapee]

Hello, Ive been trying to figure out for a couple days now on how to make summoned mobs after 35 seconds target the boss and start casting a chain heal. And I cant figure out how to get the mobs target the boss. Any help? Or suggestions on where to look?

[Scapee]

Bump
At the moment I am trying to get this to work instead:

  Creature* Coldworm; //Declare Coldworm to be able to use him 
					instance = me->GetInstanceScript();
					Coldworm = ObjectAccessor::GetCreature(*me, instance->GetData64(DATA_COLDWORM));
					Coldworm->MonsterSay("Heal me my minions!", LANG_UNIVERSAL,NULL);
					Coldworm->SetHealth(Coldworm->GetHealth() + me->GetHealth());

I have GetData function properly defined in the Instance main script and such.
If someone can tell me what im dong wrong would be nice