The North American League Championship Series got a whole lot tougher this weekend as a flurry of roster transactions bolstered the rosters of prime contenders like Team Solomid and Dignitas.

The upcoming Summer Split determines which three teams advance to the highly competitive World Championships, so teams are gearing up to battle for their shot at a world title.

Counter Logic Gaming, the third place team from the Spring Split, revealed their intention to bring in Korean top laner Shin “Seraph” Woo Yeong for a tryout last week, in an ambitious bid to bolster the talent of their roster.

Their long-time rivals would not sit by quietly, however.

Team Solomid made one of the biggest moves of the offseason after the surprise retirement of long-time jungler Brian “TheOddOne” Wyllie, adding European jungler Maurice “Amazing” Stückenschneider to the team. The German left Copenhagen Wolves to join the second ranked American squad, who hopes the addition will boost them from the top of North America to the top of the world. 

Stückenschneider has big shoes to fill. The departing Wyllie is one of the original League pro gamers, the last remaining original member of TSM dating back to Season One in 2011. “The General," as fans affectionately call him, had suffered a decline in play as the LCS competition level increased in recent seasons.

Wyllie believed stepping down was the best way to make that happen. “With our current roster, we can definitely be top two in North America, but I want TSM to be the best team in the world,” he said.

The addition of Amazing isn’t the only surprising move for TSM. One week after benching support Alex “Xpecial” Chu, still considered the player top at his position in the region, the team announced the results of their subsequent tryouts, adding Nicolas “Gleebglarbu” Haddad as their new support.

Playing with top Challenger team Cloud 9 Tempest this past season, the hard-working Haddad just barely missed qualification for the LCS. But his work ethic, attitude, and high solo queue ranking gained TSM’s attention.

The team had been unhappy with Chu’s attitude. And Haddad had better synergy with lane partner Jason “WildTurtle” Tran during tryouts.

“[Chu] is an amazing player, but just because you have the best players on a team does not mean you have the best team,” said TSM owner Andy “Reginald” Dinh.

Chu will be joining Team Curse, becoming the latest in a line of revolving supports. While Michael “BunnyFuFuu” Kurylo, the fourth support of Curse’s Spring Split, seemed to lock down the position, performing admirably with duo lane partner David “Cop” Roberson, Chu was a talent too good to pass up.

“We are excited to sign a world-class support player,” said Steve Arhancet, Team Curse's support player. “He has proven he has the skill, experience and, above all, the drive and hunger to take our team to Worlds in the Summer Split.”

“This was not an easy decision to make, as Bunnyfufuu has shown to be a very strong player with a massive amount of potential.”

Dignitas made their own splash, revamping their roster by adding the solo laners from relegated Team Coast. Top laner Darshan “ZionSpartan” Upadhyaya and mid laner Danny “Shiphtur” Le will add fresh blood to a team falling behind the increasingly tough LCS competition.

Le and Upadhyaya were the two shining stars on the failing Team Coast. Upadhyaya ranked second in the league with 28 solo kills against two deaths, while Le placed sixth with 11 kills and five deaths.

New mid lander Le replaces Dignitas captain William “Scarra” Li, who will stay on as coach. “Roster changes alone won’t bring a team to the top,” Li said on Twitter. “I’m in the process in creating an actual full support staff for the team.”

Li could be instrumental in integrating the two new players into the new Dignitas lineup, which CLG coach Christopher “MonteCristo” Mykles says still has “shot calling issues.” Still, if Le and Upadhyaya can provide the individual performances they did for Coast, Dignitas should be a contender for a spot in Worlds next season.

Thatmake the NA LCS a tough scene for Evil Geniuses, who narrowly avoided relegation by beating Cloud 9 Tempest in their promotion game.

As such, EG is holding tryouts to decide the fate of their jungler and duo laners, the three former CLG Europe players who left Europe to compete in America at the end of last year.

“While it's not pleasant having to potentially part from people you've played with over two years, this still remains a job and a competition,” said Mitch “Krepo” Voorspeols, EG support and one of the players in question, “I do believe we'll all mature enough to understand that and not hold grudges.”

All the roster action means defending champions Cloud 9 will have the longest running stable roster in the league next season, and with good reason—they’ve gone undefeated in each of the past two playoffs. But with the other LCS teams making strides, they may not take their third.