Praetor Challenge: Word Bearers vs World Eaters

On a near airless moon, Lorgar leads his mutated followers against Angron and his crazed World Eaters! But what should they do?

It is the Word Bearers to play. The set up is as see at the start of the Word Bearers movement phase. 

Word Bearers:

1x Angron. [He has a summoning reading for a unit of 5x daemons - NB]. Unwounded. 
5x Gal Vorbak. 1 of them is down to 1 wound remaining. 

World Eaters:
1x Leviathan Dreadnought with grav flux bombard and storm cannon. 2 wounds remaining. 

1x Angron. 4 wounds remaining. 

6x Tartaros terminators. 5x Lightning Claws [1 has 1 wound remaining], and 1x Praetor with Paragon Blade (counts as) with 2 wounds remaining.  

The dreadnought LITERALLY is sat on top of an objective. Not that many of the participants seem to care!

What is the best play for the Word Bearers?

Internet kudos points await! (Only redeemable with your own friends when you boast to them about Warpstone Flux's Praetor Challenge ;).