Well my wizard character learned Safety Wall lv.10 now that I have enough budget to buy tens of thousands of blue gemstones. According to the formula on iRO wiki, this spell at lv.10 is supposed to have a durability of at least 10000, and with my current level, INT and SP stats it should have durability near 20000.
http://irowiki.org/wiki/Safety_Wall
However, I find out that the safety wall disappears quickly when large number of mobs gang up on me, even if their hits are weak and do normally 200-300 HP damages. I found another source on RebirthRO wiki, which shows Safety Wall can only sustain 11 hits. If this is true, it will make Safety Wall a worse alternative than Fire Wall.
http://wiki.rebirthr...iki/Safety_Wall
So I wonder, is the information on iRO for Safety Wall still valid? I have to say Safety Wall is very hard to cast properly when facing a large number of mobs, since it will be harder to locate the exact spot my character steps on. I am using it since I believe it is characterized by durability as described by iRO wiki, but I will not use it if its charactered by hits.