Yeah, finally found time to write something. Busy with both Pokemon and Monster Hunter 4. Working to get an Excavation set of Kirin U in Monster Hunter, breeding in Pokemon.
Image from the Wiki, BTW.
So yeah, proof of my Lv100 Guild Quest. And yes, I did level up online. That is the whole point, after all.
So anyways, in the Guild Quests, once you reach a certain level (around 70~80s), every monster gets a new move or two.
For Teo, his new move is to claw and sprinkle powder in front of him and immediately clamp his jaws together, causing a small explosion. To be honest, I found the move fairly weak, as it only hits in front of him and gives him an opening. Even upon being clawed, you should be able immediately dodge away, especially if you have an Evasion+ skill.
The key to defeating high level Teos is very simple, thus probably making him the easiest of the ancient dragons of the Guild Quests. The key is to avoid his tackles. Despite the fact his signature move is to cause explosive powder, it turns out that these moves are actually the weakest moves, because it activates slowly and leaves him open to attacks, except for the version where he spreads powder near him. Also, it is very easy to tell where the explosions will occur. The most dangerous explosion is with no doubt the version where he flies up and self-destructs. While it is indeed easy to avoid, thanks to the lag before the attack occurs and the signs, if you are using a weapon that can't easily change from attack to evasion, you will occasionally be unable to avoid the attack. With no doubt, one hit kills. And because it causes Burn and Knocked Out, even skills that prevent your death will be no good.
The tackles on the other hand do not leave him open to attacks. On high levels, it does more than half your HP with one strike and when he is angry, he will occasionally charge at a player more than once a time, which will cause him to strike a player after striking him once already, which would kill the player. If you can avoid that, you should be plenty fine.
On Solo, only one player is forced to face this onslaught of attacks, which is deadly, but on Multi, his attacks generally switch targets, giving enough time to heal or shake off slime/bomb.
One motivation for doing Teo's quest is that his Guild Quest gives out special Tickets, that unlock the EX Kaiser series.