If I understand correctly you want incoming traffic for 201.131.189.0/24 to come from ISP2 under normal conditions and if ISP2 fails, then traffic for that prefix should then come from ISP1.
You almost got it right, judging from your diagram and prefixes announced.
All you need to do is on Router2 only announce:
201.131.188.0/22
201.131.189.0/24
And on Router1 only announce:
201.131.188.0/22
201.131.188.0/24
201.131.190.0/24
201.131.191.0/24
This way you influence incoming traffic for 201.131.189.0/24 to prefer ISP2 while for all other /24 prefixes it will prefer ISP1.
If ISP2 fails, there will be the /22 already announced from router1, so traffic for 201.131.189.0/24 will come from ISP1.
If ISP1 fails, there will be the /22 already announced from router2, so traffic for the rest of the /24 prefixes will come from ISP2.
Keep in mind that what you announce influences only incoming traffic.
Outgoing traffic by default will go through whichever ISP sends you the shorter AS path for a given destination prefix (among other criteria for BGP best path selection - read here
https://help.mikrotik.com/docs/display/ ... hSelection ). That's the same for all prefixes.
If you want 201.131.189.0/24 to only go out through ISP2, you could make a mangle rule to mark that traffic (routing mark) and route it through a default gateway route to ISP2 on a separate routing table with ping check enabled. If ISP2 stops responding to pings, you can have a second default gateway (with higher distance value) to ISP1, so it can fall back to.
But that will not account for failures further down the line that ISP2 might have, so the outgoing traffic will keep trying to go over ISP2, even if incoming traffic may have already failed over to ISP1. So not ideal. Maybe only for short-term situations where you are on top of it and disable it if something goes wrong with ISP2.
On the other hand, if you need to influence incoming traffic for this specific /24 in order to balance incoming traffic so ISP1 doesn't get saturated, you probably (depending on what type of traffic/users/etc) don't have to force outgoing traffic through ISP2 as well, if your outgoing traffic isn't too much.
The traffic will be asymmetric, but it probably already is anyway to an extend, since you have 2 upstream providers.
Asymmetric traffic is common-place on the internet, so you shouldn't have any noticeable impact.