>Are counterspells worth running in multi?
Only a few per deck, but yes. The conditions are that the counter must be an unrestricted hard counter, and generally it must have an upside. Some that I'd usually consider
>Arcane Denial
Cheap, replaces itself, and in multi giving the guy you scorned cards is fairly acceptable, unlike in a duel where it's a fairly crippling flaw. Probably the counter I most run thanks to having basically all the advantages when you just want that one silver bullet to stop an incoming game loss.
>Counterspell
Doesn't usually make the cut, its only virtue is being mana-cheap. That said, it is mana-cheap and totally unrestricted so it could make the grade, especially in a blue deck.
>Memory Lapse
Also doesn't usually make the cut, because its situational, but it's still worth considering since sometimes top-of-deck is a far worse place to put something than the graveyard.
>Mana Drain/Spell Swindle
Basically the same card. True, Swindle costs 5 instead of 2 which is significant but it also gets you any-color mana, that you can use immediately or later, in the form of artifacts rather than straight colorless on your next main. It's also not Gorillion Dollars like Mana Drain. Both are pretty awesome counters because they set you up.
>Spelljack
As long as you don't point it at somebody's commander like an idiot, this is a favorite of mine since it gives you such massive value. It really hurts to hold back 6 if you're not in Flash Tribal, though, so I'll often consider it, then pass it over.
>Cryptic Command
Heavy Blue devotion (both 3 symbols and 75% of its cost) so it really hurts in multicolor decks and probably doesn't show its face there but as a counter+ it does really, really funny things. True, the most common mode selection is probably counter/draw to get an Arcane Denial that doesn't help anybody else but I'm also a fan of counter/bounce to answer two problems or counter/tapdown to open up the board.