Knight of the Reliquary

Tricks (general):

You can also accelerate for a turn. Tap your mana into the pool and then tap the Knight to search for another untapped land and float another mana.

Fetching up Bojuka Bog to remove graveyards.

Fetch all sorts of utility lands in general (Karakas, Gaea's Cradle, Maze of Ith, Wasteland,

Horizon Canopy, Bojuka Bog, Arena, Kessig Wolf Run)

Sacrifice a Dryad Arbor: remove Bridge from Below at instant speed.

Your opponent has cast a sweeper. Turning a land into a manland.

Tricks (attack / block):

Fetching up Sejiri Steppe to give it protection.

Tricks (attack):

The "end of combat Maze of Ith" trick. Swing with it, run through the combat step, deal damage and move to the end of combat step. As the end of combat step is still part of the overall combat phase, its still technically an attacker, even if it's already dealt its damage, so you can use Maze of Ith to untap it without losing your damage. You can then use KotR's ability, or KotR has got vigilance.

Tricks (block):

Declare as blocker, tap and sacrifice a land, get a fetchland / Horizon Canopy: instant +2/+2
Declare as blocker, tap and sacrifice a land, get a Wasteland / Ghost Quarter, waste another  land of yours (if you can afford it): instant +3/+3

Sylvan Library

Your life total shouldn't matter to you until you're on the verge of receiving lethal damage. Obviously you shouldn't be throwing away 4 life on a whim every time, but the whole point of this card is to generate advantage by having access to cards that could lead you to a win. At worst, you're simply re-arranging what you'll be getting in subsequent turns, still giving yourself access to more information that you wouldn't otherwise have.

Most of the time you're just drawing 3 and putting 2 back. After that, use one of your deck's many shuffle effects to randomize the top card again. The next draw phase, you'll see 3 brand new cards and choose the best.

Also, against any control or combo deck that doesnt care about your life total much you can just pay 16 life over a few turns and bury your opponent in card advantage.

Against Combo for example. I may NEED a disruption spell so I pay the 8 just fine.

Mindbreak Trap

They play a bunch of stuff, which probably will include Duress or Silence or Orim's Chant, then play Tendrils of Agony, putting a pile of copies (at least 9) of tendrils on the stack, then you can, in response (if they haven't wrecked your hand or chanted you), play Mindbreak trap for 0, Exiling all copies of Tendrils on the stack at the same time as Tendrils itself. They still have the possibility of playing a second tendrils, or disrupting your trap with countermagic.

Umezawa's Jitte

You basically want to equip and attack with basically any creature you can. Getting counters on your Jitte is vital and essentially any creature will do.

Basically you never want to use any counters on Jitte and want to build it up so that its unprofitable for your opponent to play creatures. As mentioned above, use the counters as removal as required.

Jitte's ultimate is when you can swing and pump with enough counters to do lethal.

The general rule is that you only use the life gain ability when Jitte is in the process of being destroyed or in response to a burn spell or attack that will kill you.

You use the -1/-1 ability on relevant threats. This varies deck to deck, but killing most Elves/Goblins on sight is usually ideal.

You can attack with a creature equipped with Jitte and then move Jitte to an untapped creature so you can block and get more counters.

One of the best tricks is to equip it to a first striker. After first strike damage, you get the counters and can finish off a larger creature before your creature takes normal damage.