Hey!
There are 8 types of TimeSpace Rifts.
The 6 Normal racial one and 2 Star Rifts.
If you have multiple Rifts on the Screen you can merge them but be warned :
If you merge a Special Rift with normal rifts, it will become the normal rift.
Merging rifts gives you starting bonuses like Bonus Dmg or starting with More Zenkai energy.
If you can, then merge multiple black stars with each other, but this is very rare to happen.
The Black&White and the Blue&Gold Rifts are the Star Rifts.
The Most Intresting is the Black&White Rift cause you can recriurt all the Important Canon Characters (Goku,Vegeta,Whis,Broly etc....).
In The Blue&Gold rift there are just normal Characters which are Recriutable, there is no Canon characters in there.
If there is a Golden star next to the Picture of the Character, you can recriut him.
You recriut a char by Finishing him off with a Zenkai Attack. Some Chars you have to kill several times. The higher the Dmg you deal with the Zenkai Attack - the higher is the chance of recriuting the Char!
ProTips :
The Radars Scans for WiFis in your near location. The more WiFis the more Rifts will appear. If you dont have that many in your Location, than try to turn on the Hotspot feature on your Mobile Phone and on your PC / Notebook. Ask your Fam for opening a Hotspot for the moment. More -> Better. With the Neigbours Wifis i have about 5 - 10 wifis in my Area.
Unconfirmed Protipp:
Some ppl claim that Calling a Wifi "AttWifi" will give you more Star Rifts. I dont know if thats true, still im using the "trick" lol.
ProTip for Recriuts:
Get 1 - 2 Support Chars. Support AOE Moves are the fastest way to boost your Zenkai. AOE Attacks can boost your zenkai pretty fast too, but not as fast as support moves AND you could kill a char you want to recriut.
If you dont want to attack, cause you could kill a char, just charge your Ki. Or try to teach your chars some Support moves.
Healing is important, cause trying to recriut all 5 of the chars, can take very long.
Some of the chars has to be unlocked in the story or by side quests before they can be recriuted in the Radar!
Ive never encountered an Special Star :( If you did, tell me about it in the comments!