You can connect jump leads without a spike protector to any car.
Pos dead battery, pos good battery, neg good battery, neg to a suitable earth on car with flat battery.
If you disconnect any lead while engine is running you will create a high voltage spike that will find an earth, generally in some expensive item. Voltage is electrical pressure. If it's flowing and you break the circuit, the pressure increases & breaks stuff. Much like blocking a hose suddenly & having the end fly off.
Always let vehicles run for a while when connected, maybe 5-10 mins, then try & start flat car if you can.
TURN BOTH CARS OFF before you disconnect leads in exactly the opposite order as you put them on.