Why is Sejuani-Teemo a Thing?

I think 'Nexus-Strike' needs to be Sejuani's Frost because the control on auto--freeze every game mainly when she is with a Teemo which can seemingly be played 3 times in a row in decks of cards 40 & above. Especially after having to focus on him as an elusive is quite ridiculous, alongside the fact that you get a million free popper-puffs so most every card is getting 1 puff on it. As you go through cards the probability increases drastically that you're going to get boned out of the game and simply become infinitely controlled as even with only drawing a single card you're about to get frostbitten to 0 damage... 

- Draw a card, get frozen, play one hero or supporting unit, kill it or use a spell to draw a card, then maybe play one final unit - that's the only unit you get to attack with.
- It's obviously worse when you're defending because you basically can't or you just take full damage and all of their heroes & units are still alive at the end of combat.
- Hero combinations such as Yasuo can barely do anything already against these guys... but I'd need to be Demacia or something with him just to buff him 3 or 4 times after he became frost-bitten just to then scrape by mana to get a stun out. But by that point you've used all of your '1-Mana Cost Stuns'. You're left with Arachnoid from Demacia which is a 3-Mana summon instead of spell even though the 1-Mana spell is a Slow one. Or even worse you're forced to use a '4-Mana Recall' just to remove a single threat.

Quote From Cronkonium

... Teemo which can seemingly be played 3 times in a row in decks of cards 40 & above. 

Very interested to hear how one can play a deck over 40 cards from the start.

Noxus has the best anti-Teemo cards including:
Blade's Edge, Death Lotus, Culling Strike, Whirling Death, Death's Hand just to name a few.

There are so many ways to deal with Teemo. If your deck doesn't ping, challenge, give vulnerable, play AoE or whatnot then consider yourself countered. 

Quote From Hellcopter

Noxus has the best anti-Teemo cards including:
Blade's Edge, Death Lotus, Culling Strike, Whirling Death, Death's Hand just to name a few.

I don't quite see how Whirling Death could be considered an anti-Teemo card. If anything, it's worse against him than most other units in the game because if Teemo attacks alone, you can't play it (unless you have an elusive unit to block, in which case you wouldn't need Whirling Death in the first place).

Blade's Edge and Death Lotus are excellent in the early game, but won't single-handedly do the job once Teemo has leveled up. Just mentioning that for completeness' sake.

Lucky me, I haven't played against this deck archetype yet. It sounds like an awful time.

Quote From BlueSpark

Lucky me, I haven't played against this deck archetype yet. It sounds like an awful time.

I think the reason you haven't run into this archetype is because, despite the OP's sentiments, its not very good.  There is TONS of removal in the meta now, so Teemo decks in general aren't very viable (which is a shame IMHO because he's the card that otherwise could really punish all these Toss decks).  And Sejuani isn't that hot either--she actually is the most successful with decks that just use her L1 form as removal + a 5/6 overwhelm body, almost entirely ignoring her level up ability.   She's just too slow to deal with the likes of aggro burn and Bannerman 2.0, and doesn't generate enough value to deal with the likes of Sea Monsters and Mill-kai.

Quote From sinti

Speaking off, how does it work when you Toss a card with puffcaps on it? Does it fizzle out or does it damage your Nexus?

The shrooms are gone without damage.  The advantage of a Teemo deck is that doubling 10 shroom across 15 cards is just as deadly as doubling 20 across 30 cards.  Otherwise: if you're counting on your shrooms for damage, against a Toss deck you'll generally want to save them until late game. 

Quote From sinti

Speaking off, how does it work when you Toss a card with puffcaps on it? Does it fizzle out or does it damage your Nexus?

Shrooms are not actually connected to cards. What means that created cards can have shrooms on them and tossed cards never have shrooms on them. So no toss doesn't counteract puffcap