Instead of fancy pants Mikrotik guru solutions from the getgo, lets approach this from a requirements perspective.
a. WAN1 shall only be used for two external destination IP addresses
b. WAN2 shall be used for all other external destination IP addresses
c. WAN2 shall not be used for the two "special" destination IP addresses"
d. by inference: No Fail Over is required (1-->2). If WAN1 is down, the two destination IP addresses will not be available period (not even through WAN2.
e. by inference: No Fail Over is required (2-->1). If WAN2 is down, ONLY the two destination addresses will be available and through WAN1.
Now go design the fancy pants solution.
my stealing guess:
assuming ether1=WAN1=ISP1
assuming ether2=WAN2=ISP2
/ip firewall address list
add special_sites address=10.10.10.1
add special_sites address=10.10.10.2
/ip firewall NAT
add chain=srcnat action=srcnat dest-address=192.168.1.1 (ether1-ISP1)
add chain=srcnat action=srcnat dest-address=172.10.10.1 (ether2-ISP2)
/ip route
add dest-address=0.0.0.0/0 gatewayIP (of ISP2) distance=1
add dest-address=10.10.10.0/30 gatewayIP (of ISP1) distance=1
/ip firewall filter
FORWARD CHAIN order
- drop invalid
- accept established, connected, untracked
- accept in-interface=LAN destination-address-list=special_sites out-interface=ether1
- accept in-interface=LAN destination-address-list=! special_sites out-interface=ether2
- log log=yes prefix="VIEW ALL BEING DROPPED TO CONFIRM"
- drop all else