the Dark Angle is a high risk high reward champion with great mobility and burst. He thrives in the middle lane as an assassin. As a gold dependent champion he needs gold to be sufficient in the middle and late game to do as much damage as possible. Sanguinarius scale well of AP and his E also scales of AD. The purpose of the Dark angle is to assassinate enemy squishes and get out before your killed.
Sanguinarius is probably a weak laner due to his long cooldowns and short range. You should farm as much as possible and stay safe until you get your items. Try to harras with Q-Q-E- Combo and use your W to restore your health when you get out of range. Sanguinarius is weak in lane vs champs with cc and range and strong vs melee champs with no escapes.
In the middle game its Sagnarius time to shine. By this you should have built lich bane and Deathfire Grasp. You can snowball your lanes really hard with his brutal burst and mobility. Try to do as much damage to other team as possible in this phase as teamfights will be rare and they will probably have little cc to lock you down with. Seize turrets and take objectives and carry your team.
Sagnarius is still very strong in the late game but needs his team to engage or he is dependent on picking out squishy targets. As Sagnarius you should concentrate your entire combo on one squishy target and burst it down. Kill the squishy with your ult so you can get that invisibility to get out of the fray.
-High mobility -High burst -No mana -Very strong snowballer -One of the best 1 vs 1 champs in the mid game. -Great single target damage -W sustain to survive -Godlike midgame
-No CC -High risk -Easily locked down by CC -Weak early game -Long cooldowns -Very Squishy -Item dependent