sIKE, I'm no expert with FM like you. But all my FM builds have always used this trick. What happens is this...
I am within 3 of a big threat (say Vampiric Bear Strength Grizzly), have Initiative and, due to the QC Force Pull then attack tactic of FM, I have 18 mana in my pool. I choose Mind Control and Mordok's Obelisk in Planning.
After my first action, when I am now adjacent to threat, I QC Mind Control on threat and reveal it (pay 2+8) to Stun the threat before it acts. Unless opponent has Dispel ready, I Final QC Obelisk to let it die before opponent can Dispel the Mind Control. The Obelisk now deters swarm so I threaten any other over-invested threat. No book can really afford more than 2 Mind Controls at 6 spell points each (Obelisk is another 4 but always good for FM). Also there is a lot of popular Psychic Immunity out there so investing points like this is a big risk.
FM player should not telegraph by casting Obelisk first (it should always be cast Final QC before Upkeep to mess up opponent's plans).
It's not that great: you spend alot of mana and spell points, so only really good against an over-buffed creature (Wizard has Purge Magic). For 6 spell points, 16 mana and 2 quick actions, FM can cast Sleep + Quicksand to remove an isolated level 4 threat. Although there are lots of outs there (Teleport solves almost all problems).
They have costed "removal" tricks at roughly the same cost as the threat you remove (just like Dispel/Dissolve).
Now, I've never thought about Mind Shield before (Wildhorn's proposal). It's a pretty specific counter for 2 spell points. Anyone who plays Enchanter's Ring (FM's other ring) and enchantments will probably use Decoys instead of Seeking Dispel to trigger Nullify (save points, deter Seeking Dispel, make 1 mana). Mind Shield like Retaliate is not mandatory, you don't need to trigger it to Charm (which can always guard or attack other objects). It's good when a card I'd dismissed as too niche is proved useful. That is if you're regularly facing this trick. Shame it doesn't get round Nightshade Lotus which is a poison attack.