Trampling Charge

If the warbeast moves at least 20 ft. straight toward a creature and then hits it with a hooves attack on the same turn, that target must succeed on a DC 14 Strength saving throw or be knocked prone.  

Trained Companion

When any creature of your choice including you is mounted on the warbeast, the rider and warbeast both gain a +2 armor class bonus. Additionally, if the rider makes an attack action on the warbeast's turn, they can add the warbeast's CON to the attack roll.   Upon reaching 6th level, choose one of the abilities below to add to your warbeast.  

Nightmarish Lineage

The warbeast unlocks a deeper part of itself, drawing on the fire from the hells below. Upon taking this feature, the warbeast gains an appearance similar to that of a Nightmare. Additionally, the warbeast gains resistance to fire damage and now can cast the Dragon's Breath spell once per long rest, but can only use the fire damage option. The warbeast uses your spellcasting ability for this spell. Also, the hooves attack action deals an additional 1d6 fire damage.   If the warbeast also has the Unborn Wings feature, the wings which are spawned can be feiry instead of ghost-like.  

Supporting Mount

While a creature is mounted on the warbeast, they gain a +2 damage bonus to all attacks they make on the warbeast's turn. Also, when the warbeast takes this feature, its hit point maximum changes to being equal to half your level d12 + CON + 2.  

Unborn Wings

Prerequisite; 6th level As an action on the warbeast's turn, or as a command on your turn, the warbeast sprouts ghost-like wings for 5 minutes, granting it a flying speed equal to half its walking speed.