The answer from the Crusaders coach came quickly: "Our forwards and our defensive systems."
Both true, but he could have added another - the Crusaders' attack - because his side won't be able to rely solely on his big men and the tackling ability of his players in this sudden death play-off at AMI Stadium.
Time and again the Crusaders have the edge in the forwards battle - and so they should with eight current or former All Blacks in the mix - but that dominance doesn't always translate to success.
While his pack scrummaged well against the Hurricanes in the nervous 26-17 victory last weekend, the lineout had an off day. A big improvement is needed there, which the returning Luke Romano is likely to help with.
Yes, the Crusaders' defence is good. In terms of points conceded they are the fourth best in the competition with 307. However, the Reds have a better record here - 296, one point behind the Brumbies (295) and four behind the Stormers (292), a team just outside the playoffs.
The crux of the matter is the Crusaders need their attack to fire and once again the onus will go on Dan Carter to provide the kindling and matches. Israel Dagg has an important role to play here too, but it's Carter who sets the standard. When he's in the mood and takes the ball to the line - like he did recently against the Chiefs - Blackadder's team look like world-beaters.
When he doesn't, they look like something else entirely. Rather than attacking with width, the backs tend to pass the ball for the sake of it. They'll be easy pickings for a connected Reds' team organised by the incomparable Will Genia.
Carter is the Crusaders' point of difference and time is running out on him adding another championship to the titles he won in 2005, 2006 and 2008. Next year's sabbatical will rule him out of the 2014 competition and, fitness permitting, his return to Super Rugby ahead of the World Cup in 2015 could be his last shot before a move overseas.
The last time the Crusaders played the Reds was at AMI Stadium last year, a 15-11 victory for the home team which Blackadder described this week as a "slugfest". Significantly, Carter played at second-five that day, with first-five Tom Taylor's goalkicking getting them home - he kicked five penalties.
The Crusaders last year scored only two tries in their two play-off matches - one in their 28-18 qualifier win over the Bulls (who scored two) and one in their 20-17 semifinal defeat to the Chiefs (who also scored two).
Reds coach Ewen McKenzie has proven to be an extremely good student of an opposition's game plan - he worked the Chiefs out before his side's 31-23 victory in Hamilton this season.
It's all adding up to another tight match on Saturday - unless the attacking ability of Carter and Co gives the Reds a scare or two.
