Champion key is 8 wins.
Straight from a Hearthstone Wiki
Wins Key No.** Possible rewards
0 Novice 2 A pack and 25-40 gold or dust or a common card.
1 Apprentice 2 A pack and 30-50 gold or dust or a common card.
2 Journeyman 2 A pack, and either 40-50 gold or dust, or a common or rare card.
3 Copper 3 A pack and 25-35 gold, plus either about 20-25 dust or gold, or a common or rare card.
4 Silver 3 A pack and 40-60 gold, plus either about 20-25 dust or gold, or a common or rare card.
5 Gold 3 A pack and 50-60 gold, plus either about 45-60 dust or gold, or a common or rare card.
6 Platinum 3-4 A pack and 75-85 gold, plus one or two prizes from the following*: about 50 dust or gold, and regular or golden common or rare card.
7 Diamond 3-4 A pack and about 155 gold, and one or two of the following*: about 25 dust or gold, and common, rare and golden cards.
8 Champion 3-4 A pack and about 155 gold, and one or two of the following*: 25 dust, 20-40 gold, and a regular or golden variation of any card.
9 Ruby 3-4 A pack, about 155 gold, and one or two of the following*: 50 dust, 75-95 gold, and a regular or golden variation of any card.
10 Frostborn 3-4 A pack, about 180 gold, and one or two of the following*: 70-90 dust, 65-115 gold, a golden common, and regular or golden variation of any card, rare or above.
11 Molten 3-4 A pack, about 200 gold, and one or two of the following*: 60-90 dust, 80-180 gold, a golden common, and regular or golden variation of any card, rare or above.
12 Lightforge 5 A pack, about 230 gold, and three of the following*: another pack, 20-25 dust, 20-175 gold, a golden common, and regular or golden variation of any card, rare or above.
* Each reward can appear multiple times
** Number of rewards
There are no particular combinations, it depends entirely on whether your opponents play enough weapons for him to be worth it.
Harrison Jones is a 5/4 minion for 5 mana. You can get a 4/5 Chillwind Yeti for 4 mana, which is probably one of the best plain minions. Compared to that Harrison Jones is not a very good minion if you don't get to trigger his special ability. But a 5/4 for 5 mana is also not terrible.
But I think you're underestimating the value you got in the situations where you played him. Even one card drawn and 1 durability destroyed is a pretty good outcome. You denied your opponent card advantage they might have gotten from using their weapon a second time, and you gained 1 card advantage yourself from drawing a card. That is pretty good already.
The situations where Harrison Jones would be devastating would be enemies that use the following weapons:
- Paladin: Sword of Justice 1/5
- Shaman: Doomhammer 2/8
- Warlock: Lord Jaraxxus 3/8
- Rogue: Assassins Blade 3/4
- Paladin: Light's Justice 1/4
Harrison Jones is a very situational card. It depends entirely on the current meta and the opponents you face whether it makes sense to use him in your deck. In a very weapon-heavy meta he can be very useful, against a weaponless opponents he's a rather expensive and mediocre 5 drop.
Best Answer
Upon death of the cube you will get 2 original copies of M, regardless of what the stats of M are when the cube consumed it (silenced, damaged, buff cards, etc).
Example 1: You copy a Bonemare as a 1/1. If you cube the 1/1 Bonemare when the Cube dies you will get 2 5/5 Bonemares on the board.
Example 2: You copy an Edwin Vancleef as a 1/1. But it gets buffed to a 5/5 in your turn. Next turn you attack a minion and it goes down to a 5/2. You cube him. The cube dies, you get 2 2/2 Edwin Vancleefs on the board.