Its better to give
But bear in mind: creatures exiled with ice counters on them are still exiled, so even if your necromancer is slain before he has the chance to resurrect anything, you've still removed those creatures from enemy graveyards
Sakashima is currently the most expensive Partner in the game, and with good reason
Since dashing is still casting the spell just for a different cost, you still add the appropriate commander tax onto the cost that you pay when you dash based on how many times you already cast the commander
Black Knight is great against Blue/White Control, Mono White, and any other deck that relies on Swords to Plowshares, Wrath of God, and Balance for creature removal (under Alpha rules, protection from white makes Black Knight immune to Wrath of God and Balance)
And true, you could play in drafts which are nice because they put everyone on the same level playing field, but you're still paying $15 to buy more cards when you already have cards at home