Abilities

since bosses doesn't fall, 

and players fall with just one point on this skill and the time down will be the same, be it with 1 or 5 points, so not worth wasting more than 1 point on it.

only used while hidding, it means you'll use it only one time per battle.

SHOULD get

because it will be a constant damage on monster or player.

AoE Abilities

Spread Poison and get more combo points depending on the quantity of monsters surrounding you.

Cooldown Abilities

grants you 3 combo points, should only be used if you have less than or 2 combo points, if you use that with more than 2 you'll kinda waste a cooldown.

High damage, ALWAYS use that when out of cooldown.

Set of cards

those cards alone give you just 41 agi and 41 str, but the sum of +23 bonus of each stats raise it to 64 with only 3 cards leaving up to you to decide the other two cards.

best suvivability [28 vit] and good agi and str.

i don't know if it will give you twice the bonus of cards, if does not, just use Wild Feral Barbaro Card [rare+] that IMO is one of the best balanced card for assassins, same agi and str, with 20 vit and you'll also reach an excelent result.