During the first years of MW's existence, Teleport has been the card that could wreck "turtle" or "Fortress" builds.
In the meantime, the power of Teleport has been recognised and some countermeasures have been released.
So, is it easier now to build up strongly in 1 zone ?
I'm not sure, as a new turtle-breaker has arrived : Chant of Rage.
Since this spell is Lvl1 Mind or Dark, the two mages to benefit from it the most imo are the Forcemaster and Arraxian Crown Warlock. Both can easily carry 4 of these for just 4 sbp's and seriously disrupt the opposing mage's build up. (I see the number of CoR's go up in my books any time I play anyway)
( Siren is the third mage that can use it cheaply as she is Trained in Songs )
Instead of having to take on the opposing stronghold head-on, you can instead "cherrypick" from among the opposing creatures and make them come to you. ( divide and conquer )
This is a "must-react-to" play for the opponent that is likely going to cost him at least as much mana and likely more sbp's than you put into it or risk losing the creature if he doesn't react to it.
This works smoothly for the FM + Alandell book I have.
You can even cast the Chant of Rage from far away through a Mind's eye and set up Alandell ( or even a Spore ) with the hate token.
Being so cheap sbp wise you can load up on Rages and repeat multiple times, potentially forcing the enemy out of Dispels which may come back to bite him later.
Another thing to consider is that the best counters to Chant of Rage also belong to the mind school with Clear Mind and Mind Shield.
Another potentially very strong strategy imo is to let Chant of Rage combo with Rise Again.
Curseweaving makes the Arraxian Crown Warlock the ideal Mage for this strategy.
Use Chant of Rage to bring opposing living creatures to you and your Reaper, kill them and bring them back as Zombies with Rise Again. Build yourself an army using your opponent's actions and creatures and bring them to your side.
4 Chant of Rage + 2 Rise Again costs only 10 sbp's for an AC Warlock to include in his Spellbook.
Considering how powerful the combo can be, there's just no reason not to include it in your AC Warlock book, I think.