Generally, each team has one jungler, which means that there will be one lane of two, and two lanes of one. Since the middle lane will always be a solo lane, this means that top and bottom will have varying numbers of champions, depending on the lane.
Top is usually considered a solo lane because the bottom lane is closer to Dragon, an important mid-game objective. Dragon is hard to solo for most non-junglers, and by keeping 2 champions in the bottom lane, it becomes quite viable to 3-man Dragon after a successful gank (or simply a double-kill). While top lane is closer to Baron Nashor, it takes quite a bit more effort to kill him - more than 3 champions in the early game can probably afford to put out. By the time Baron becomes available, the game is usually nearing the end of the laning phase, after which the difference between top and bottom lane is moot (because all 5 champions are roaming).
With a top solo lane, the champion has a leveling advantage and the potential to farm more minions (simply because there is no allied champion to compete with). Additionally, one must consider that if the other team does not have a jungler, they need to be able to successfully last 2 vs. 1. Most often, this means champions with good sustainability are better suited to the lane, such as Cho'goth, Mordekaiser, Vladimir, or Nasus.
Conversely, there are some champions who do not do well in a solo lane - these tend to be support champions like Soraka, Sona, or Janna who perform much better with a partner to buff/shield/heal. These champions usually go to the bottom lane to ensure that they are in a 2 vs. 2 situation.
In instances where there is no jungler on either team, both top and bottom will have an even number of champions. In this case you may be asked to "switch lanes" not because one lane is "better suited" than the other, but because switching lanes means changing which enemy champions you're fighting (and presumably, have been dying to).
Displacement effects (knock ups, knock backs, etc) are not affected by tenacity or any crowd control clearing effects like Cleanse or Quicksilver Sash. Displacements effects can be prevented by spell-shields however, like Banshees Veil and Morgana's Black Shield.
Suppression effects involve a channel by the caster and can only be stopped in one of three ways:
- Quicksilver Sash
- Gangplank's ability Remove Scurvy
- An ally canceling the caster's channel with a hard stun, silence, or displacement
Best Answer
Pulsefire got its own category because of the features associated with it.
Most legendary skins change how the champion acts (voice, spell, etc), while Pulsefire changes not only Ezreal's appearance, but other champion's animations as well. Enemy champions and minions killed by Pulsefire Ezreal have a unique death animation.
In addition to this, the skin itself evolves and changes its appearance further as you level up Ezreal's ultimate.
There is actually a very interesting post on the League of Legends forum explaining some of the design choices, including a developer commentary on the creation of Pulsefire Ezreal.
In addition to this, it adds a new Profile scheme as mentioned by Patrick Stadler.
Also, in lieu of more text, have this cropped photo of Ezreal's crotch along with a description of all of the features involved in his theme:
As for whether or not the Themes will periodically be placed on sale, there is currently no answer. My best guess would be that they are going to be similar to Legendary skins in that they do not go into a usual sale cycle like regular skins. Only time (and a few additional Theme releases) will tell.