If you have warcaster, polearm master and metamagic adept you can't boost charisma until 16th level, or 12th if you are a variant human or custom. At this point you are playing against many enemies with true sight or devils sight, both of which mean they will see as good as you in the magical darkness.Lance is a skin of table. (It's a glaive weapon).
PAM and Warcaster works by RAW and RAI.
I already play with Metamagic Adept and Boosting Cha.
Have you actually played it? I don't think it is going to OP or "insane" against large numbers of enemies. Against a single enemy that is not strong enough to grapple you sure. I don't believe magical guidance will work as well as you think and it costs a sorcery point. Unless you have a high athletics or acrobatics, even with that you will still lose often and when that happens you will be quickly overwhelmed. Not to mention you won't actually have SPs to use magical guidance since they will be used up.Thanks.
The Sorcerer just hit and run. The Darkness moves with him, the hound (with advantage) and allies can attack normally without disadvantage. It's not 100%, but It just move out and your friends will do their job normally.
If the enemy is prone because your hound does, just cast a saving throw spell (applying disadvantage). It's so flexible.
If the enemy doesn't come close enough, just cast firebolt or empowered fireball like a standard sorcerer does, but with advantage on attack rolls and applying disadvantage against your spells.
The idea here is, if the threatining enemy tries come close enough, It's dead.
"Finally they can also grapple you and then move you out of the darkness. All of these things involve wasted turns for the enemy, so it is not ideal for them, but they will try to counter your power base."
It doesnt work, because the darkness moves with the weapon. Also, Sorcerer's Magical Guidance helps him on skills checks. It isn't a good idea.
The Sorcerer can dash, move to a better position or just "bye" and still cast quicken empowered fireball.
It isn't unkillable, but It isn't easy to defeat.
Based on your scenarion on turn one you burn 2 SPs to cast your magical darkness and another 3 to summon your hound. An enemy comes at you and you use empower schorching ray and burn another SP. Then you burn 2 more to quicken a spell on your turn. Guess what your 8th-level sorcerer is out of sorcery points and you are only in the second turn of combat for the entire day.
The sorcerer only has a 30 move (barring bonuses from other classes). You can dash, but that is a lost action and will typically require another dash to get back into range to make PAM work.