The Best Trinkets for WoW Rogue

1. Mjolnir Runestone : It gives a chance on hit to increase your armor penetration by 612 for 10 seconds and increases your critical strike rating by 102 .

Note : While the proc from this and Grim Toll do stack, they will push you well over the armor penetration cap and thus waste what could be a much more beneficial buff. So upgrade Grim Toll's .
 
2. Blood of the Old God : It increases your chance to hit by 108, and can proc a 1284 AP buff on crit.

Pyrite Infuser the same as the above only 95 hit and 1234 AP buff.

Just a lot of hit to help us hit the cap, and a buff that puts the Mirror of Truth to shame.  The pyrite infuser is much easier to get however, as a simple 10 man Flame Leviathan normal drop.
 
3. Wrathstone : It increases your critical strike rating by 108, and can activate for a 856 AP buff for 20 seconds with a two minute cooldown .A lot of Attack Power and Crit.

The downside is you need to keep hitting this trinket every time it's up to see the full value of it in long boss battles, where as if you hit it once and forget about it, you might be better off keeping one of the previous tier trinkets in the slot.
 
The hardest boss will be dropped off by this trinket but as for the rest of them they aren't always heroic or hard mode!  Keep your poison hit cap in mind as you're grabbing these.  Even if we get more white damage out of hit beyond that point, striking with every blow for pathetic damage simply doesn't work.