league-of-legends
I always lose when I am against a tristana, never won a single lane against her.
Fact is that I find her not predictable: she just farms and gets harrassed by me, then she decides that it is enough, so jump+E first kill.
No matter how much I harrass her, my impression is that I am under her control and I die when she decides to…
AD Nidalee excels at her laning phase, however, she falls behind quite significantly during mid/late game. If you notice that the Nidalee is equally or more skilled than you are, you should play passive, since it is highly unlikely that you can trade with her efficiently. Do not go for last hits if the risk is too high.
Once you hit mid/late-game, you should be ahead, even though you might be behind her in CS, due to the fact that Riven brings a lot more to teamfights than AD Nidalee.
Wish you the best of luck versus them Nidalees!
Sivir's Boomerang Blade can be an annoying harass, both at early level and late game. Unfortunately, it mostly takes practice to be able to avoid it. But there are a couple of tips that I think (hope) will be helpful in the long run.
Sivir's Boomerang Blade has a fairly large attack radius. Where you are in relation to where Sivir is when she launches the attack can make a fairly significant difference. The important thing to remember, though, is the further you are from her, the longer you have to react. Try to remain at a distance as much as possible when facing Sivir; especially in early game. One more important point on placement, the more minions between you and Sivir, the less damage you will receive if Boomerang Blade hits you. Each enemy it hits makes the damage to the next enemy lessen.
Unfortunately for you, sometimes dodging her initial attack ins't always enough. Her blade will track with her, if she moves up or down on the battlefield. You should always move in the opposite direction from Sivir. In the following image, consider your Champion to be X, while the colored arrows show the path of the blade upon return, in relation to Sivir's movement.
One last point worth mentioning is this: While the camera is zoomed in in that image, it's important to remember the high range of Boomerang Blade. It will extend to the far edge of the screenshot.
If you can't always avoid the first shot, pay close attention to avoiding the return strike. But in the end, it really comes down to practice, practice, practice.
Best Answer
The best way to learn a champion's weaknesses is to play that champion until someone beats you. That will show you how it is done.
This is not always an accessible solution - most recent champions cost a lot of IP. But in this case, Tristana is very cheap and there is a permanent promotion which will unlock her + a skin for free.
Writing speculatively, rocket jump has less base damage than explosive shot, but gains 5 more damage per rank than explosive shot does & deals damage up front, so the all-in style of Tristana play likely prioritizes ranks in jump. This means that anything which allows you to get out from under the jump and avoid its damage will save you from death. Rocket jump's animation is long enough to permit reacting with flash, but that has a much longer cooldown than rocket jump. Champions Ezreal, Lucian & Corki have their own move skills which act quickly enough to get you out. Caitlyn also has a move block but there's a windup animation, which may prevent you from getting out in time to avoid the impact damage.