@Phoenixflambe  

 
That was PRECISELY what confirmed my hypotesis (that is now a full fledged Theory for any further analysis of the franchise that would involve “Tirek Titan Mode”).  
-> He is CONSTANTLY shooting his beam while clenching his teeth (but the only things he is shooting at is trees & rocks (if you freezeframe you can see some rocky debris flying out besides roots & dirt).
 
The location were the destruction happened is also relevant: Historically there were no other buildings NEXT to the “pond” from where the Castle of Friendship & cutiemap grew up [some of the trees he is destroying needed more time to get to that size/width than the few years that passed since the no_Sonic-Rainboom].
 
If he was just “angry” at someone or something, he would not be also moving around the direction of his “beam of destruction” [he would just direct his anger agains “something” specific (either to destroy it or push it)].  
-> Instead he was trying to avoid MELTING more of the bedrock (likely the source of the “red glow” & the dense “ashy” atmosphere), by spreading around his energy release until he could stop for long enough to start moving towards the ocean [the only heatsink big enough that could permanently sustain his “runaway powersurges”].

@Argamis  
What about the alternate timeline Starlight created?

@Phoenixflambe  

 
Tirek was not omnicidal on porpouse. That was just a side effect of becoming a “Titan” [too much magic inside of him constantly building up energy surges that MUST be “vented out” or will make him explode].  
This is why he was constantly shooting beams to trees & rocks in wild places (his real desire was to RULE creatures, but it will be too dangerous for them if he was around civilized spaces).  
-> Shooting “to space” would not work (the beams can push stuff, so they must contain some mass & those were not moving at speeds grater than escape velocity), as it will just be like “raining death” on random directions across the world [likely killing innocents]; he is a noble, honorable LORD (not a mindless beast or a force of nature).
 
This is also why he choose to NOT take “all” of the magic of Grogar contained in the Bewitching Bell for himself (since it was an unknown ammount, it could posibly be something beyond his ability to control), wisely splitting it on equal parts with Chrysalis & Cozy [so at least they would be able to “cancel each others out” if it was necesary until they figure out how to “recontain it”].

It’s so pointless that life is pointless that he would destroy all of it? How’s that for motivation?

@Background Pony #C1D0  

 
Certainly, someone has to plant the ideas in Tirek’s mind about how to use his magic to steal other people’s magic and thus show him how he can fulfill his ambitions to show his father his own power behind his back. According to the IDW comics, Sendak the elder had to live in exile in the Nether Lands, although his freedom of movement was not restricted, obviously he had a criminal background which made King Vorak not trust the older magician. Which was why Scorpan had at the beginning of IDW: Fiendship is magic # 2 warned his brother from going there, the father had suspected that Sendak had taken Tirek as his student, and thus feared what the older centaur was teaching his son. It turned out to be justified.
 
Before FiM # 2, Sendak and Tirek had planned to abduct a pony from Equestria to complete their studies on how to take all the magic from some of the most magical creatures in the world. Since magic was little valued in King Vorak’s kingdom - it seems that there is simply too little magic in everyday life beyond certain talents related to species affiliation - beings from the most magical country in the world must be abducted to the Nether Lands. By this time, Tirek had learned the technique of draining the inner magic of a living being - but as Sendak noted, he was still too young, impatient and not strong enough to face a pony that was likely to have greater magical power than usual. Sedak could use the technique flawlessly in contrast to his student.
 
Sendak will of course contact the prince for his own gain, but it is also possible that he saw the potential in the young centaur and wanted to design him as his student and possibly successor, he had begun to draw on his age. Tirek will see the possibility of becoming stronger and more powerful, and thus surpassing his father, by making use of his magic in open defiance. But it is obvious that this could not be hidden from King Vorak as Tirek did not seem to want to hide his training with Sendak and even took Scorpan with him. I think Tirek did it on purpose with a childish urge to show defiance and opposition to his authoritarian father, and thus the relationship would sour while Sendak trained the prince.
 
All villains have a beginning. It’s right now this one has started for Tirek.

Interesting. If you look at his dresser, he has several awards and trophies. Yet none of it is good enough for Vorak…or Tirek.

No matter what he does, his father will never be impressed by his achievements.

I can understand why he’s so frustrated. I wonder if Sandek will make an appearence here.