A magnetically-guided catheter (100) includes a tip positioning magnet in the distal electrode assembly (112) configured to interact with externally applied magnetic fields for magnetically-guided movement. A magnetically-guided mapping catheter (100) includes an electrically-conductive capsule in the form of a casing (146) that includes a distal ablation surface and isolates the positioning magnet from bio-fluids to prevent corrosion. An irrigated ablation catheter includes a manifold (206) isolating the positioning magnet(s) from contact with irrigation fluid. Devices and methods for manufacturing magnetically driven electrode-catheter with flexible tethering includes one or more fibers, distributed centrally or peripherally within a catheter shaft and oriented longitudinally, transversely, angularly or spirally. A C-shaped extruded catheter introducer (and re-introducer) includes a longitudinally-extending opening for insertion of a magnetically-guided catheter, removal of the introducer from the catheter and constructed to facilitate its re-use.