What is the deff killa wartrike?

I’m an AOS player maybe doing a 1k builders league. My idea is to do a pig themed army with old world boar boys (bikes or squig hog boys) and AOS big pig. Is the deff killa wartrike a hero/character I can have as my warlord? Tried googling and didn’t really understand. Or should I do a proxy for beastboss on squigisaur. Thanks in advance for helping a noob