Magic the Gathering is one of the best designed games of all time, as well as one of the longest games in development. With more than 20 years under it’s belt, Magic design has become a science and therefore it is not surprising to find synergies between cards and mechanics across multiple sets printed one after another. A good example of this is the new Prowess mechanic spoiled for Khans of Tarkir, which allows creatures get become stronger when their controllers cast spells. This blatantly works well with the Heroic mechanic from the previous block, Theros, which allows creatures to become stronger when their controllers cast spells that target them.
The last set to be released in Magic the Gathering was the Magic 2015 Core Set, which brought back the Convoke mechanic from the original Ravnica block. Convoke is very popular and strong, as it allows players to tap their creatures to cast spells with the Convoke keyword. Spells like Triplicate Spirits and Siege Worm are powerful spells with Convoke, but the downside is that a player must tap their creatures. This may be considered a very small side effect, as Convoke allows creatures to act like Elvish Mystics for their color, but being tapped still leaves you open to spells like Assassinate and stops you from blocking.
During the release of Born of the Gods players were curious how to make the new Inspired mechanic work well without attacking. Inspired caused mechanics to trigger when a creature untapped, which means that that creature must first be tapped. Obviously attacking without vigilance is the most simple way to tap a creature, but other options were also available, such as Springleaf Drum. Now that Magic 2015 re-released the Convoke mechanic, players trying to break the Inspired mechanic have another option for tapping their creatures. Whether this synergy is actually worth the effort is still up for discussion, but it is a good example of soft synergy between two sets that are both Standard legal.