He wants hasty or flash creatures, who are dying, and artifacts that produce mana, ideally for spells that take the most advantage of split second
This ink is frequently found in the top 4 of tournaments and is one-half of the most popular deck archetype: Bounce Control
As theyre so widely available, and each card is a reprint of one previously issued, they tend to be extremely cheap and easy to collect
(It can't be blocked except by creatures with flying or reach.) Creature - Human Assassin Color tag templates(None) Island Basic Land - Island Color tag templates(None) Merciless Harlequin Freerunning (You may cast this spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander.) When this creature enters, you draw a card and you lose 1 life
They have sweepers, but you can fight through those
Couple this with the ablity to move all damage and potentially send a character to the discard pile, and it's easy to see why it's so valuable