Life Cost 0 is the most recommended skill viable for a specific deck like Ultimate Cyber-Stein. However, this skill might never get on top of the tier. A very unique skill in current skill pool of duel links’s.
You have to pay 5000 apparently, it's so freaking cheap!
I only just managed to beat a mako deck that was using this skill, I was so lucky, its too OP. he had 500lp, i had 4000 with a 2500ATk dragons vanguard and a michizure set plus a flamvell grunika in my hand. He used the skill with cyber sten to summon Master of OZ and blue eyes ultimate, only survived by destroying oz with michizure and only won as i dreew riyoku, lucky since he had mirror wall