Summoned my first and only Guan Yu on my 11th summon. Did not summon Izumi at all.
Benchmark still remains as 10(from previous Summoning video) to summon a Rate Up Hero i.e. after being unable to summon a Rate Up Hero 10 times, on the 11th draw, you will get a Rate Up Hero.
Assumption: the 10 times resets after every event i.e. the counter starts from zero again after every event.
Notable Hero mentions i.e. Heroes that are commonly used
1) Merlin Warlock (Arena)
Uses: Kill and displace Tanks as well as to break up formations of Trigger teams
Talent: Resistance/Survival/Fortification
Equipment Suffix: Defence
Runes: Defence
Example:
https://imgur.com/a/2cbTF
2) Lucille Archbishop, Luthor Archbishop, Matilda Spirit Walker
Uses: Attackers in Healer team
Talent: Weapon Mastery/Attunement/Enchantment
Equipment Suffix: Might
Runes: Attack
Example:
https://imgur.com/imgyJ1U