He has Roy Krishna, Nathan Burns, Tyler Boyd, Kenny Cunningham and Brockie among those he could use in his front three.
"It's about goal-scoring now so it's about who can play in those positions up front," Merrick said.
The Phoenix will be without midfielder Albert Riera and right back Manny Muscat for the meeting with Adelaide given they will be on duty with the A-League's All Star line-up as they prepare for their clash with Juventus in Sydney on August 10.
Michael Boxall seems a logical choice to fill the void in the defensive line left by Muscat, while Merrick may use Riera's absence to promote a player like teenager Alex Rufer.
"I think it's a good opportunity for a number of the younger boys to step up," Merrick said.
Long-time starting midfielder Vince Lia remains sidelined with a leg injury, while new signing Roly Bonevacia probably won't arrive in Wellington for another week or two.
The A-League All Stars are coached by Adelaide's Josep Gombau, who will miss the FFA Cup game against Wellington, while Adelaide players Eugene Galekovic and Marcelo Carrusca will also skip the knockout clash due to their All Star commitments.
Tuesday's match will be played at the Marden Sports Complex rather than Adelaide's normal home ground of Coopers Stadium.
Following qualifying among lower-league teams in Australia, the FFA Cup has reached the round of 32 when the A-League sides join the tournament.
Meanwhile, the ongoing contract saga around Michael McGlinchey will rumble into next week with arbitration set to continue.
Both the Phoenix and the Central Coast mariners believe they have the All Whites midfielder under contract for the upcoming season but he wants to play for Wellington.