Hey, Level 50 Medic here. Couple of things, if you want Kaliyo to tank, make sure she has a SHIELD equip and NOT a Generator or a Vibroknife. Very, very important. Second, make sure you focus on +defense, +shield absorb and endurance items. Also armor is probably the most important stat. If it has higher armor, it's probably better. Personally though, I just used Vector. Make sure he is in his Combat Pheremone's stance, the 10% healing is quite noticeable and it's the main reason I preferred Vector. To me, Kaliyo absolutely holds aggro better than Vector and she also has more AoE options, but Vector required less healing and generally did better dps. Also, me tanking instead of my companion works wonders. Maybe the best way to explain things is to work from the mindset of "glass canon", just blow things up before they get to you. Also, for the love of god, USE YOUR STUNS. Every single time there's a "strong" NPC (the ones with blue) make sure your stun(s) is up. Another important thing. Don't try to play ranged. Sniping works at lower levels, but you need to be in melee range to use your Stun and also to Backstab/Shiv/Hidden Strike/Sleep Dart/Carbine Burst. If there's a pack of 4-5 mobs, make sure Evasion is up. Use it on the pull. Remember, your 5-s stun is on a 45s cd (30s talented) and your Evasion (100% Dodge) is on a 60s cd. You can pretty much always use at least one. Lastly, once I got Ensign Raina Temple, I just used her. She does superior DPS to Vector and it's far easier to gear her. She's squishier for sure, but I can tank so she can blow **** up.