Thanks to PsychicNature for suggesting this mega!

Entai recently has become one of my favorite fire legendaries due to the fact that it learns sacred fire, making ho-oh not the only one.

Entai gains the sheer force ability which makes its moves like sacred fire, extrasensory, and lava plume more powerful, but removes their added effects, so you really should choose wether you want to mega evolve Entai or not. It gets boosts in all of its stats, but primarily its offensive ones. It also remains a pure fire type. Its appearace changes to where it is now more legendary looking, with 2 coils around each leg rather than one. Its mane is more impressive and its body takes on a more reddish tint. It has ribbons of fire surrounding it.
Stat boosts:
20 attack
25 sp attack
15 defense
25 speed
15 sp defense